SYNOPSIS

tor &lsqb;OPTIONvalue]…

DESCRIPTION

Tor is a connection-oriented anonymizing communication
service. Users choose a source-routed path through a set of nodes, and
negotiate a "virtual circuit" through the network, in which each node
knows its predecessor and successor, but no others. Traffic flowing down
the circuit is unwrapped by a symmetric key at each node, which reveals
the downstream node.

Basically, Tor provides a distributed network of servers or relays ("onion routers").
Users bounce their TCP streams — web traffic, ftp, ssh, etc. — around the
network, and recipients, observers, and even the relays themselves have
difficulty tracking the source of the stream.

By default, tor will act as a client only. To help the network
by providing bandwidth as a relay, change the ORPort configuration
option — see below. Please also consult the documentation on the Tor
Project’s website.

COMMAND-LINE OPTIONS

-h, -help

Display a short help message and exit.

-fFILE

Specify a new configuration file to contain further Tor configuration
options OR pass - to make Tor read its configuration from standard
input. (Default: @CONFDIR@/torrc, or $HOME/.torrc if that file is not
found)

--allow-missing-torrc

Do not require that configuration file specified by -f exist if
default torrc can be accessed.

--defaults-torrcFILE

Specify a file in which to find default values for Tor options. The
contents of this file are overridden by those in the regular
configuration file, and by those on the command line. (Default:
@CONFDIR@/torrc-defaults.)

--ignore-missing-torrc

Specifies that Tor should treat a missing torrc file as though it
were empty. Ordinarily, Tor does this for missing default torrc files,
but not for those specified on the command line.

List all valid options that are scheduled to become obsolete in a
future version. (This is a warning, not a promise.)

--version

Display Tor version and exit.

--quiet|--hush

Override the default console log. By default, Tor starts out logging
messages at level "notice" and higher to the console. It stops doing so
after it parses its configuration, if the configuration tells it to log
anywhere else. You can override this behavior with the --hush option,
which tells Tor to only send warnings and errors to the console, or with
the --quiet option, which tells Tor not to log to the console at all.

--keygen &lsqb;--newpass]

Running "tor --keygen" creates a new ed25519 master identity key for a
relay, or only a fresh temporary signing key and certificate, if you
already have a master key. Optionally you can encrypt the master identity
key with a passphrase: Tor will ask you for one. If you don’t want to
encrypt the master key, just don’t enter any passphrase when asked.

The --newpass option should be used with --keygen only when you need
to add, change, or remove a passphrase on an existing ed25519 master
identity key. You will be prompted for the old passphase (if any),
and the new passphrase (if any).

When generating a master key, you will probably want to use
--DataDirectory to control where the keys
and certificates will be stored, and --SigningKeyLifetime to
control their lifetimes. Their behavior is as documented in the
server options section below. (You must have write access to the specified
DataDirectory.)

To use the generated files, you must copy them to the DataDirectory/keys
directory of your Tor daemon, and make sure that they are owned by the
user actually running the Tor daemon on your system.

--passphrase-fdFILEDES

Filedescriptor to read the passphrase from. Note that unlike with the
tor-gencert program, the entire file contents are read and used as
the passphrase, including any trailing newlines.
Default: read from the terminal.

--key-expiration &lsqb;purpose]

The purpose specifies which type of key certificate to determine
the expiration of. The only currently recognised purpose is
"sign".

Running "tor --key-expiration sign" will attempt to find your signing
key certificate and will output, both in the logs as well as to stdout,
the signing key certificate’s expiration time in ISO-8601 format.
For example, the output sent to stdout will be of the form:
"signing-cert-expiry: 2017-07-25 08:30:15 UTC"

Other options can be specified on the command-line in the format "--option
value", in the format "option value", or in a configuration file. For
instance, you can tell Tor to start listening for SOCKS connections on port
9999 by passing --SocksPort 9999 or SocksPort 9999 to it on the command line,
or by putting "SocksPort 9999" in the configuration file. You will need to
quote options with spaces in them: if you want Tor to log all debugging
messages to debug.log, you will probably need to say --Log debug file
debug.log.

Options on the command line override those in configuration files. See the
next section for more information.

THE CONFIGURATION FILE FORMAT

All configuration options in a configuration are written on a single line by
default. They take the form of an option name and a value, or an option name
and a quoted value (option value or option "value"). Anything after a #
character is treated as a comment. Options are
case-insensitive. C-style escaped characters are allowed inside quoted
values. To split one configuration entry into multiple lines, use a single
backslash character (\) before the end of the line. Comments can be used in
such multiline entries, but they must start at the beginning of a line.

Configuration options can be imported from files or folders using the %include
option with the value being a path. If the path is a file, the options from the
file will be parsed as if they were written where the %include option is. If
the path is a folder, all files on that folder will be parsed following lexical
order. Files starting with a dot are ignored. Files on subfolders are ignored.
The %include option can be used recursively.

By default, an option on the command line overrides an option found in the
configuration file, and an option in a configuration file overrides one in
the defaults file.

This rule is simple for options that take a single value, but it can become
complicated for options that are allowed to occur more than once: if you
specify four SocksPorts in your configuration file, and one more SocksPort on
the command line, the option on the command line will replace all of the
SocksPorts in the configuration file. If this isn’t what you want, prefix
the option name with a plus sign (+), and it will be appended to the previous
set of options instead. For example, setting SocksPort 9100 will use only
port 9100, but setting +SocksPort 9100 will use ports 9100 and 9050 (because
this is the default).

Alternatively, you might want to remove every instance of an option in the
configuration file, and not replace it at all: you might want to say on the
command line that you want no SocksPorts at all. To do that, prefix the
option name with a forward slash (/). You can use the plus sign (+) and the
forward slash (/) in the configuration file and on the command line.

GENERAL OPTIONS

A token bucket limits the average incoming bandwidth usage on this node
to the specified number of bytes per second, and the average outgoing
bandwidth usage to that same value. If you want to run a relay in the
public network, this needs to be at the very least 75 KBytes for a
relay (that is, 600 kbits) or 50 KBytes for a bridge (400 kbits) — but of
course, more is better; we recommend at least 250 KBytes (2 mbits) if
possible. (Default: 1 GByte)

Note that this option, and other bandwidth-limiting options, apply to TCP
data only: They do not count TCP headers or DNS traffic.

With this option, and in other options that take arguments in bytes,
KBytes, and so on, other formats are also supported. Notably, "KBytes" can
also be written as "kilobytes" or "kb"; "MBytes" can be written as
"megabytes" or "MB"; "kbits" can be written as "kilobits"; and so forth.
Tor also accepts "byte" and "bit" in the singular.
The prefixes "tera" and "T" are also recognized.
If no units are given, we default to bytes.
To avoid confusion, we recommend writing "bytes" or "bits" explicitly,
since it’s easy to forget that "B" means bytes, not bits.

If set, we will not advertise more than this amount of bandwidth for our
BandwidthRate. Server operators who want to reduce the number of clients
who ask to build circuits through them (since this is proportional to
advertised bandwidth rate) can thus reduce the CPU demands on their server
without impacting network performance.

If not 0, a separate token bucket limits the average incoming bandwidth
usage for _relayed traffic_ on this node to the specified number of bytes
per second, and the average outgoing bandwidth usage to that same value.
Relayed traffic currently is calculated to include answers to directory
requests, but that may change in future versions. (Default: 0)

If set, do separate rate limiting for each connection from a non-relay.
You should never need to change this value, since a network-wide value is
published in the consensus and your relay will use that value. (Default: 0)

If set, do separate rate limiting for each connection from a non-relay.
You should never need to change this value, since a network-wide value is
published in the consensus and your relay will use that value. (Default: 0)

ClientTransportPlugintransport socks4|socks5 IP:PORT

ClientTransportPlugintransport exec path-to-binary &lsqb;options]

In its first form, when set along with a corresponding Bridge line, the Tor
client forwards its traffic to a SOCKS-speaking proxy on "IP:PORT".
(IPv4 addresses should written as-is; IPv6 addresses should be wrapped in
square brackets.) It’s the
duty of that proxy to properly forward the traffic to the bridge.

In its second form, when set along with a corresponding Bridge line, the Tor
client launches the pluggable transport proxy executable in
path-to-binary using options as its command-line options, and
forwards its traffic to it. It’s the duty of that proxy to properly forward
the traffic to the bridge.

ServerTransportPlugintransport exec path-to-binary &lsqb;options]

The Tor relay launches the pluggable transport proxy in path-to-binary
using options as its command-line options, and expects to receive
proxied client traffic from it.

ServerTransportListenAddrtransportIP:PORT

When this option is set, Tor will suggest IP:PORT as the
listening address of any pluggable transport proxy that tries to
launch transport. (IPv4 addresses should written as-is; IPv6
addresses should be wrapped in square brackets.)

ServerTransportOptionstransportk=vk=v …

When this option is set, Tor will pass the k=v parameters to
any pluggable transport proxy that tries to launch transport.
(Example: ServerTransportOptions obfs45 shared-secret=bridgepasswd cache=/var/lib/tor/cache)

ExtORPort &lsqb;address:]port|auto

Open this port to listen for Extended ORPort connections from your
pluggable transports.

ExtORPortCookieAuthFilePath

If set, this option overrides the default location and file name
for the Extended ORPort’s cookie file — the cookie file is needed
for pluggable transports to communicate through the Extended ORPort.

ExtORPortCookieAuthFileGroupReadable0|1

If this option is set to 0, don’t allow the filesystem group to read the
Extended OR Port cookie file. If the option is set to 1, make the cookie
file readable by the default GID. &lsqb;Making the file readable by other
groups is not yet implemented; let us know if you need this for some
reason.] (Default: 0)

ConnLimitNUM

The minimum number of file descriptors that must be available to the Tor
process before it will start. Tor will ask the OS for as many file
descriptors as the OS will allow (you can find this by "ulimit -H -n").
If this number is less than ConnLimit, then Tor will refuse to start.

You probably don’t need to adjust this. It has no effect on Windows
since that platform lacks getrlimit(). (Default: 1000)

DisableNetwork0|1

When this option is set, we don’t listen for or accept any connections
other than controller connections, and we close (and don’t reattempt)
any outbound
connections. Controllers sometimes use this option to avoid using
the network until Tor is fully configured. (Default: 0)

ConstrainedSockets0|1

If set, Tor will tell the kernel to attempt to shrink the buffers for all
sockets to the size specified in ConstrainedSockSize. This is useful for
virtual servers and other environments where system level TCP buffers may
be limited. If you’re on a virtual server, and you encounter the "Error
creating network socket: No buffer space available" message, you are
likely experiencing this problem.

The preferred solution is to have the admin increase the buffer pool for
the host itself via /proc/sys/net/ipv4/tcp_mem or equivalent facility;
this configuration option is a second-resort.

The DirPort option should also not be used if TCP buffers are scarce. The
cached directory requests consume additional sockets which exacerbates
the problem.

You should not enable this feature unless you encounter the "no buffer
space available" issue. Reducing the TCP buffers affects window size for
the TCP stream and will reduce throughput in proportion to round trip
time on long paths. (Default: 0)

ConstrainedSockSizeNbytes|KBytes

When ConstrainedSockets is enabled the receive and transmit buffers for
all sockets will be set to this limit. Must be a value between 2048 and
262144, in 1024 byte increments. Default of 8192 is recommended.

ControlPortPORT|unix:path|auto &lsqb;flags]

If set, Tor will accept connections on this port and allow those
connections to control the Tor process using the Tor Control Protocol
(described in control-spec.txt in
torspec). Note: unless you also
specify one or more of HashedControlPassword or
CookieAuthentication, setting this option will cause Tor to allow
any process on the local host to control it. (Setting both authentication
methods means either method is sufficient to authenticate to Tor.) This
option is required for many Tor controllers; most use the value of 9051.
If a unix domain socket is used, you may quote the path using standard
C escape sequences.
Set it to "auto" to have Tor pick a port for you. (Default: 0)

Recognized flags are…

GroupWritable

Unix domain sockets only: makes the socket get created as
group-writable.

WorldWritable

Unix domain sockets only: makes the socket get created as
world-writable.

RelaxDirModeCheck

Unix domain sockets only: Do not insist that the directory
that holds the socket be read-restricted.

ControlSocketPath

Like ControlPort, but listens on a Unix domain socket, rather than a TCP
socket. 0 disables ControlSocket (Unix and Unix-like systems only.)

ControlSocketsGroupWritable0|1

If this option is set to 0, don’t allow the filesystem group to read and
write unix sockets (e.g. ControlSocket). If the option is set to 1, make
the control socket readable and writable by the default GID. (Default: 0)

HashedControlPasswordhashed_password

Allow connections on the control port if they present
the password whose one-way hash is hashed_password. You
can compute the hash of a password by running "tor --hash-password
password". You can provide several acceptable passwords by using more
than one HashedControlPassword line.

CookieAuthentication0|1

If this option is set to 1, allow connections on the control port
when the connecting process knows the contents of a file named
"control_auth_cookie", which Tor will create in its data directory. This
authentication method should only be used on systems with good filesystem
security. (Default: 0)

CookieAuthFilePath

If set, this option overrides the default location and file name
for Tor’s cookie file. (See CookieAuthentication above.)

CookieAuthFileGroupReadable0|1

If this option is set to 0, don’t allow the filesystem group to read the
cookie file. If the option is set to 1, make the cookie file readable by
the default GID. &lsqb;Making the file readable by other groups is not yet
implemented; let us know if you need this for some reason.] (Default: 0)

ControlPortWriteToFilePath

If set, Tor writes the address and port of any control port it opens to
this address. Usable by controllers to learn the actual control port
when ControlPort is set to "auto".

ControlPortFileGroupReadable0|1

If this option is set to 0, don’t allow the filesystem group to read the
control port file. If the option is set to 1, make the control port
file readable by the default GID. (Default: 0)

DataDirectoryDIR

Store working data in DIR. Can not be changed while tor is running.
(Default: ~/.tor if your home directory is not /; otherwise,
@LOCALSTATEDIR@/lib/tor. On Windows, the default is
your ApplicationData folder.)

DataDirectoryGroupReadable0|1

If this option is set to 0, don’t allow the filesystem group to read the
DataDirectory. If the option is set to 1, make the DataDirectory readable
by the default GID. (Default: 0)

When we’re unable to connect to any directory cache for directory info
(usually because we don’t know about any yet) we try a directory authority.
Clients also simultaneously try a FallbackDir, to avoid hangs on client
startup if a directory authority is down. Clients retry FallbackDirs more
often than directory authorities, to reduce the load on the directory
authorities.
By default, the directory authorities are also FallbackDirs. Specifying a
FallbackDir replaces Tor’s default hard-coded FallbackDirs (if any).
(See the DirAuthority entry for an explanation of each flag.)

UseDefaultFallbackDirs0|1

Use Tor’s default hard-coded FallbackDirs (if any). (When a
FallbackDir line is present, it replaces the hard-coded FallbackDirs,
regardless of the value of UseDefaultFallbackDirs.) (Default: 1)

DirAuthority &lsqb;nickname] &lsqb;flags] ipv4address:portfingerprint

Use a nonstandard authoritative directory server at the provided address
and port, with the specified key fingerprint. This option can be repeated
many times, for multiple authoritative directory servers. Flags are
separated by spaces, and determine what kind of an authority this directory
is. By default, an authority is not authoritative for any directory style
or version unless an appropriate flag is given.
Tor will use this authority as a bridge authoritative directory if the
"bridge" flag is set. If a flag "orport=port" is given, Tor will use the
given port when opening encrypted tunnels to the dirserver. If a flag
"weight=num" is given, then the directory server is chosen randomly
with probability proportional to that weight (default 1.0). If a
flag "v3ident=fp" is given, the dirserver is a v3 directory authority
whose v3 long-term signing key has the fingerprint fp. Lastly,
if an "ipv6=&lsqb;ipv6address]:orport" flag is present, then
the directory
authority is listening for IPv6 connections on the indicated IPv6 address
and OR Port.

Tor will contact the authority at ipv4address to
download directory documents. The provided port value is a dirport;
clients ignore this in favor of the specified "orport=" value. If an
IPv6 ORPort is supplied, Tor will
also download directory documents at the IPv6 ORPort.

If no DirAuthority line is given, Tor will use the default directory
authorities. NOTE: this option is intended for setting up a private Tor
network with its own directory authorities. If you use it, you will be
distinguishable from other users, because you won’t believe the same
authorities they do.

DirAuthorityFallbackRateNUM

When configured to use both directory authorities and fallback
directories, the directory authorities also work as fallbacks. They are
chosen with their regular weights, multiplied by this number, which
should be 1.0 or less. The default is less than 1, to reduce load on
authorities. (Default: 0.1)

These options behave as DirAuthority, but they replace fewer of the
default directory authorities. Using
AlternateDirAuthority replaces the default Tor directory authorities, but
leaves the default bridge authorities in
place. Similarly,
AlternateBridgeAuthority replaces the default bridge authority,
but leaves the directory authorities alone.

DisableAllSwap0|1

If set to 1, Tor will attempt to lock all current and future memory pages,
so that memory cannot be paged out. Windows, OS X and Solaris are currently
not supported. We believe that this feature works on modern Gnu/Linux
distributions, and that it should work on *BSD systems (untested). This
option requires that you start your Tor as root, and you should use the
User option to properly reduce Tor’s privileges.
Can not be changed while tor is running. (Default: 0)

DisableDebuggerAttachment0|1

If set to 1, Tor will attempt to prevent basic debugging attachment attempts
by other processes. This may also keep Tor from generating core files if
it crashes. It has no impact for users who wish to attach if they
have CAP_SYS_PTRACE or if they are root. We believe that this feature
works on modern Gnu/Linux distributions, and that it may also work on *BSD
systems (untested). Some modern Gnu/Linux systems such as Ubuntu have the
kernel.yama.ptrace_scope sysctl and by default enable it as an attempt to
limit the PTRACE scope for all user processes by default. This feature will
attempt to limit the PTRACE scope for Tor specifically - it will not attempt
to alter the system wide ptrace scope as it may not even exist. If you wish
to attach to Tor with a debugger such as gdb or strace you will want to set
this to 0 for the duration of your debugging. Normal users should leave it
on. Disabling this option while Tor is running is prohibited. (Default: 1)

FetchDirInfoEarly0|1

If set to 1, Tor will always fetch directory information like other
directory caches, even if you don’t meet the normal criteria for fetching
early. Normal users should leave it off. (Default: 0)

FetchDirInfoExtraEarly0|1

If set to 1, Tor will fetch directory information before other directory
caches. It will attempt to download directory information closer to the
start of the consensus period. Normal users should leave it off.
(Default: 0)

FetchHidServDescriptors0|1

If set to 0, Tor will never fetch any hidden service descriptors from the
rendezvous directories. This option is only useful if you’re using a Tor
controller that handles hidden service fetches for you. (Default: 1)

FetchServerDescriptors0|1

If set to 0, Tor will never fetch any network status summaries or server
descriptors from the directory servers. This option is only useful if
you’re using a Tor controller that handles directory fetches for you.
(Default: 1)

FetchUselessDescriptors0|1

If set to 1, Tor will fetch every consensus flavor, descriptor, and
certificate that it hears about. Otherwise, it will avoid fetching useless
descriptors: flavors that it is not using to build circuits, and authority
certificates it does not trust. This option is useful if you’re using a
tor client with an external parser that uses a full consensus.
This option fetches all documents, DirCache fetches and serves
all documents. (Default: 0)

HTTPProxyhost&lsqb;:port]

Tor will make all its directory requests through this host:port (or host:80
if port is not specified), rather than connecting directly to any directory
servers. (DEPRECATED: As of 0.3.1.0-alpha you should use HTTPSProxy.)

HTTPProxyAuthenticatorusername:password

If defined, Tor will use this username:password for Basic HTTP proxy
authentication, as in RFC 2617. This is currently the only form of HTTP
proxy authentication that Tor supports; feel free to submit a patch if you
want it to support others. (DEPRECATED: As of 0.3.1.0-alpha you should use
HTTPSProxyAuthenticator.)

HTTPSProxyhost&lsqb;:port]

Tor will make all its OR (SSL) connections through this host:port (or
host:443 if port is not specified), via HTTP CONNECT rather than connecting
directly to servers. You may want to set FascistFirewall to restrict
the set of ports you might try to connect to, if your HTTPS proxy only
allows connecting to certain ports.

HTTPSProxyAuthenticatorusername:password

If defined, Tor will use this username:password for Basic HTTPS proxy
authentication, as in RFC 2617. This is currently the only form of HTTPS
proxy authentication that Tor supports; feel free to submit a patch if you
want it to support others.

Sandbox0|1

If set to 1, Tor will run securely through the use of a syscall sandbox.
Otherwise the sandbox will be disabled. The option is currently an
experimental feature. It only works on Linux-based operating systems,
and only when Tor has been built with the libseccomp library. This option
can not be changed while tor is running.
When the Sandbox is 1, the following options can not be changed when tor
is running:
Address
ConnLimit
CookieAuthFile
DirPortFrontPage
ExtORPortCookieAuthFile
Logs
ServerDNSResolvConfFile
Tor must remain in client or server mode (some changes to ClientOnly and
ORPort are not allowed).
(Default: 0)

Socks4Proxyhost&lsqb;:port]

Tor will make all OR connections through the SOCKS 4 proxy at host:port
(or host:1080 if port is not specified).

Socks5Proxyhost&lsqb;:port]

Tor will make all OR connections through the SOCKS 5 proxy at host:port
(or host:1080 if port is not specified).

Socks5ProxyUsernameusername

Socks5ProxyPasswordpassword

If defined, authenticate to the SOCKS 5 server using username and password
in accordance to RFC 1929. Both username and password must be between 1 and
255 characters.

SocksSocketsGroupWritable0|1

If this option is set to 0, don’t allow the filesystem group to read and
write unix sockets (e.g. SocksSocket). If the option is set to 1, make
the SocksSocket socket readable and writable by the default GID. (Default: 0)

KeepalivePeriodNUM

To keep firewalls from expiring connections, send a padding keepalive cell
every NUM seconds on open connections that are in use. If the connection
has no open circuits, it will instead be closed after NUM seconds of
idleness. (Default: 5 minutes)

LogminSeverity&lsqb;-maxSeverity] stderr|stdout|syslog

Send all messages between minSeverity and maxSeverity to the standard
output stream, the standard error stream, or to the system log. (The
"syslog" value is only supported on Unix.) Recognized severity levels are
debug, info, notice, warn, and err. We advise using "notice" in most cases,
since anything more verbose may provide sensitive information to an
attacker who obtains the logs. If only one severity level is given, all
messages of that level or higher will be sent to the listed destination.

LogminSeverity&lsqb;-maxSeverity] fileFILENAME

As above, but send log messages to the listed filename. The
"Log" option may appear more than once in a configuration file.
Messages are sent to all the logs that match their severity
level.

As above, but select messages by range of log severity and by a
set of "logging domains". Each logging domain corresponds to an area of
functionality inside Tor. You can specify any number of severity ranges
for a single log statement, each of them prefixed by a comma-separated
list of logging domains. You can prefix a domain with ~ to indicate
negation, and use * to indicate "all domains". If you specify a severity
range without a list of domains, it matches all domains.

This is an advanced feature which is most useful for debugging one or two
of Tor’s subsystems at a time.

For example, "Log &lsqb;handshake]debug &lsqb;~net,~mm]info notice stdout" sends
to stdout: all handshake messages of any severity, all info-and-higher
messages from domains other than networking and memory management, and all
messages of severity notice or higher.

LogMessageDomains0|1

If 1, Tor includes message domains with each log message. Every log
message currently has at least one domain; most currently have exactly
one. This doesn’t affect controller log messages. (Default: 0)

MaxUnparseableDescSizeToLogNbytes|KBytes|MBytes|GBytes|TBytes

Unparseable descriptors (e.g. for votes, consensuses, routers) are logged
in separate files by hash, up to the specified size in total. Note that
only files logged during the lifetime of this Tor process count toward the
total; this is intended to be used to debug problems without opening live
servers to resource exhaustion attacks. (Default: 10 MB)

OutboundBindAddressIP

Make all outbound connections originate from the IP address specified. This
is only useful when you have multiple network interfaces, and you want all
of Tor’s outgoing connections to use a single one. This option may
be used twice, once with an IPv4 address and once with an IPv6 address.
IPv6 addresses should be wrapped in square brackets.
This setting will be ignored for connections to the loopback addresses
(127.0.0.0/8 and ::1).

OutboundBindAddressORIP

Make all outbound non-exit (relay and other) connections
originate from the IP address specified. This option overrides
OutboundBindAddress for the same IP version. This option may
be used twice, once with an IPv4 address and once with an IPv6
address. IPv6 addresses should be wrapped in square brackets.
This setting will be ignored for connections to the loopback
addresses (127.0.0.0/8 and ::1).

OutboundBindAddressExitIP

Make all outbound exit connections originate from the IP address
specified. This option overrides OutboundBindAddress for the
same IP version. This option may be used twice, once with an IPv4
address and once with an IPv6 address.
IPv6 addresses should be wrapped in square brackets.
This setting will be ignored
for connections to the loopback addresses (127.0.0.0/8 and ::1).

PidFileFILE

On startup, write our PID to FILE. On clean shutdown, remove
FILE. Can not be changed while tor is running.

ProtocolWarnings0|1

If 1, Tor will log with severity 'warn' various cases of other parties not
following the Tor specification. Otherwise, they are logged with severity
'info'. (Default: 0)

RunAsDaemon0|1

If 1, Tor forks and daemonizes to the background. This option has no effect
on Windows; instead you should use the --service command-line option.
Can not be changed while tor is running.
(Default: 0)

LogTimeGranularityNUM

Set the resolution of timestamps in Tor’s logs to NUM milliseconds.
NUM must be positive and either a divisor or a multiple of 1 second.
Note that this option only controls the granularity written by Tor to
a file or console log. Tor does not (for example) "batch up" log
messages to affect times logged by a controller, times attached to
syslog messages, or the mtime fields on log files. (Default: 1 second)

TruncateLogFile0|1

If 1, Tor will overwrite logs at startup and in response to a HUP signal,
instead of appending to them. (Default: 0)

SyslogIdentityTagtag

When logging to syslog, adds a tag to the syslog identity such that
log entries are marked with "Tor-tag". Can not be changed while tor is
running. (Default: none)

SafeLogging0|1|relay

Tor can scrub potentially sensitive strings from log messages (e.g.
addresses) by replacing them with the string &lsqb;scrubbed]. This way logs can
still be useful, but they don’t leave behind personally identifying
information about what sites a user might have visited.

If this option is set to 0, Tor will not perform any scrubbing, if it is
set to 1, all potentially sensitive strings are replaced. If it is set to
relay, all log messages generated when acting as a relay are sanitized, but
all messages generated when acting as a client are not. (Default: 1)

UserUsername

On startup, setuid to this user and setgid to their primary group.
Can not be changed while tor is running.

KeepBindCapabilities0|1|auto

On Linux, when we are started as root and we switch our identity using
the User option, the KeepBindCapabilities option tells us whether to
try to retain our ability to bind to low ports. If this value is 1, we
try to keep the capability; if it is 0 we do not; and if it is auto,
we keep the capability only if we are configured to listen on a low port.
Can not be changed while tor is running.
(Default: auto.)

HardwareAccel0|1

If non-zero, try to use built-in (static) crypto hardware acceleration when
available. Can not be changed while tor is running. (Default: 0)

AccelNameNAME

When using OpenSSL hardware crypto acceleration attempt to load the dynamic
engine of this name. This must be used for any dynamic hardware engine.
Names can be verified with the openssl engine command. Can not be changed
while tor is running.

AccelDirDIR

Specify this option if using dynamic hardware acceleration and the engine
implementation library resides somewhere other than the OpenSSL default.
Can not be changed while tor is running.

AvoidDiskWrites0|1

If non-zero, try to write to disk less frequently than we would otherwise.
This is useful when running on flash memory or other media that support
only a limited number of writes. (Default: 0)

CircuitPriorityHalflifeNUM1

If this value is set, we override the default algorithm for choosing which
circuit’s cell to deliver or relay next. When the value is 0, we
round-robin between the active circuits on a connection, delivering one
cell from each in turn. When the value is positive, we prefer delivering
cells from whichever connection has the lowest weighted cell count, where
cells are weighted exponentially according to the supplied
CircuitPriorityHalflife value (in seconds). If this option is not set at
all, we use the behavior recommended in the current consensus
networkstatus. This is an advanced option; you generally shouldn’t have
to mess with it. (Default: not set)

CountPrivateBandwidth0|1

If this option is set, then Tor’s rate-limiting applies not only to
remote connections, but also to connections to private addresses like
127.0.0.1 or 10.0.0.1. This is mostly useful for debugging
rate-limiting. (Default: 0)

ExtendByEd25519ID0|1|auto

If this option is set to 1, we always try to include a relay’s Ed25519 ID
when telling the proceeding relay in a circuit to extend to it.
If this option is set to 0, we never include Ed25519 IDs when extending
circuits. If the option is set to "default", we obey a
parameter in the consensus document. (Default: auto)

NoExec0|1

If this option is set to 1, then Tor will never launch another
executable, regardless of the settings of PortForwardingHelper,
ClientTransportPlugin, or ServerTransportPlugin. Once this
option has been set to 1, it cannot be set back to 0 without
restarting Tor. (Default: 0)

SchedulersKIST|KISTLite|Vanilla

Specify the scheduler type that tor should use. The scheduler is
responsible for moving data around within a Tor process. This is an ordered
list by priority which means that the first value will be tried first and if
unavailable, the second one is tried and so on. It is possible to change
these values at runtime. This option mostly effects relays, and most
operators should leave it set to its default value.
(Default: KIST,KISTLite,Vanilla)
The possible scheduler types are:
KIST: Kernel-Informed Socket Transport. Tor will use TCP information
from the kernel to make informed decisions regarding how much data to send
and when to send it. KIST also handles traffic in batches (see
KISTSchedRunInterval) in order to improve traffic prioritization decisions.
As implemented, KIST will only work on Linux kernel version 2.6.39 or
higher.
KISTLite: Same as KIST but without kernel support. Tor will use all
the same mechanics as with KIST, including the batching, but its decisions
regarding how much data to send will not be as good. KISTLite will work on
all kernels and operating systems, and the majority of the benefits of KIST
are still realized with KISTLite.
Vanilla: The scheduler that Tor used before KIST was implemented. It
sends as much data as possible, as soon as possible. Vanilla will work on
all kernels and operating systems.

KISTSchedRunIntervalNUMmsec

If KIST or KISTLite is used in the Schedulers option, this controls at which
interval the scheduler tick is. If the value is 0 msec, the value is taken
from the consensus if possible else it will fallback to the default 10
msec. Maximum possible value is 100 msec. (Default: 0 msec)

KISTSockBufSizeFactorNUM

If KIST is used in Schedulers, this is a multiplier of the per-socket
limit calculation of the KIST algorithm. (Default: 1.0)

CLIENT OPTIONS

The following options are useful only for clients (that is, if
SocksPort, HTTPTunnelPort, TransPort, DNSPort, or
NATDPort is non-zero):

Bridge &lsqb;transport] IP:ORPort &lsqb;fingerprint]

When set along with UseBridges, instructs Tor to use the relay at
"IP:ORPort" as a "bridge" relaying into the Tor network. If "fingerprint"
is provided (using the same format as for DirAuthority), we will verify that
the relay running at that location has the right fingerprint. We also use
fingerprint to look up the bridge descriptor at the bridge authority, if
it’s provided and if UpdateBridgesFromAuthority is set too.

If "transport" is provided, it must match a ClientTransportPlugin line. We
then use that pluggable transport’s proxy to transfer data to the bridge,
rather than connecting to the bridge directly. Some transports use a
transport-specific method to work out the remote address to connect to.
These transports typically ignore the "IP:ORPort" specified in the bridge
line.

Tor passes any "key=val" settings to the pluggable transport proxy as
per-connection arguments when connecting to the bridge. Consult
the documentation of the pluggable transport for details of what
arguments it supports.

LearnCircuitBuildTimeout0|1

If 0, CircuitBuildTimeout adaptive learning is disabled. (Default: 1)

CircuitBuildTimeoutNUM

Try for at most NUM seconds when building circuits. If the circuit isn’t
open in that time, give up on it. If LearnCircuitBuildTimeout is 1, this
value serves as the initial value to use before a timeout is learned. If
LearnCircuitBuildTimeout is 0, this value is the only value used.
(Default: 60 seconds)

CircuitsAvailableTimeoutNUM

Tor will attempt to keep at least one open, unused circuit available for
this amount of time. This option governs how long idle circuits are kept
open, as well as the amount of time Tor will keep a circuit open to each
of the recently used ports. This way when the Tor client is entirely
idle, it can expire all of its circuits, and then expire its TLS
connections. Note that the actual timeout value is uniformly randomized
from the specified value to twice that amount. (Default: 30 minutes;
Max: 24 hours)

CircuitStreamTimeoutNUM

If non-zero, this option overrides our internal timeout schedule for how
many seconds until we detach a stream from a circuit and try a new circuit.
If your network is particularly slow, you might want to set this to a
number like 60. (Default: 0)

ClientOnly0|1

If set to 1, Tor will not run as a relay or serve
directory requests, even if the ORPort, ExtORPort, or DirPort options are
set. (This config option is
mostly unnecessary: we added it back when we were considering having
Tor clients auto-promote themselves to being relays if they were stable
and fast enough. The current behavior is simply that Tor is a client
unless ORPort, ExtORPort, or DirPort are configured.) (Default: 0)

ConnectionPadding0|1|auto

This option governs Tor’s use of padding to defend against some forms of
traffic analysis. If it is set to auto, Tor will send padding only
if both the client and the relay support it. If it is set to 0, Tor will
not send any padding cells. If it is set to 1, Tor will still send padding
for client connections regardless of relay support. Only clients may set
this option. This option should be offered via the UI to mobile users
for use where bandwidth may be expensive.
(Default: auto)

ReducedConnectionPadding0|1

If set to 1, Tor will not not hold OR connections open for very long,
and will send less padding on these connections. Only clients may set
this option. This option should be offered via the UI to mobile users
for use where bandwidth may be expensive. (Default: 0)

ExcludeNodesnode,node,…

A list of identity fingerprints, country codes, and address
patterns of nodes to avoid when building a circuit. Country codes are
2-letter ISO3166 codes, and must
be wrapped in braces; fingerprints may be preceded by a dollar sign.
(Example:
ExcludeNodes ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc}, 255.254.0.0/8)

By default, this option is treated as a preference that Tor is allowed
to override in order to keep working.
For example, if you try to connect to a hidden service,
but you have excluded all of the hidden service’s introduction points,
Tor will connect to one of them anyway. If you do not want this
behavior, set the StrictNodes option (documented below).

Note also that if you are a relay, this (and the other node selection
options below) only affects your own circuits that Tor builds for you.
Clients can still build circuits through you to any node. Controllers
can tell Tor to build circuits through any node.

Country codes are case-insensitive. The code "{??}" refers to nodes whose
country can’t be identified. No country code, including {??}, works if
no GeoIPFile can be loaded. See also the GeoIPExcludeUnknown option below.

ExcludeExitNodesnode,node,…

A list of identity fingerprints, country codes, and address
patterns of nodes to never use when picking an exit node---that is, a
node that delivers traffic for you outside the Tor network. Note that any
node listed in ExcludeNodes is automatically considered to be part of this
list too. See
the ExcludeNodes option for more information on how to specify
nodes. See also the caveats on the "ExitNodes" option below.

GeoIPExcludeUnknown0|1|auto

If this option is set to auto, then whenever any country code is set in
ExcludeNodes or ExcludeExitNodes, all nodes with unknown country ({??} and
possibly {A1}) are treated as excluded as well. If this option is set to
1, then all unknown countries are treated as excluded in ExcludeNodes
and ExcludeExitNodes. This option has no effect when a GeoIP file isn’t
configured or can’t be found. (Default: auto)

ExitNodesnode,node,…

A list of identity fingerprints, country codes, and address
patterns of nodes to use as exit node---that is, a
node that delivers traffic for you outside the Tor network. See
the ExcludeNodes option for more information on how to specify nodes.

Note that if you list too few nodes here, or if you exclude too many exit
nodes with ExcludeExitNodes, you can degrade functionality. For example,
if none of the exits you list allows traffic on port 80 or 443, you won’t
be able to browse the web.

Note also that not every circuit is used to deliver traffic outside of
the Tor network. It is normal to see non-exit circuits (such as those
used to connect to hidden services, those that do directory fetches,
those used for relay reachability self-tests, and so on) that end
at a non-exit node. To
keep a node from being used entirely, see ExcludeNodes and StrictNodes.

The ExcludeNodes option overrides this option: any node listed in both
ExitNodes and ExcludeNodes is treated as excluded.

A list of identity fingerprints and country codes of nodes
to use for the first hop in your normal circuits.
Normal circuits include all
circuits except for direct connections to directory servers. The Bridge
option overrides this option; if you have configured bridges and
UseBridges is 1, the Bridges are used as your entry nodes.

The ExcludeNodes option overrides this option: any node listed in both
EntryNodes and ExcludeNodes is treated as excluded. See
the ExcludeNodes option for more information on how to specify nodes.

StrictNodes0|1

If StrictNodes is set to 1, Tor will treat solely the ExcludeNodes option
as a requirement to follow for all the circuits you generate, even if
doing so will break functionality for you (StrictNodes applies to neither
ExcludeExitNodes nor to ExitNodes). If StrictNodes is set to 0, Tor will
still try to avoid nodes in the ExcludeNodes list, but it will err on the
side of avoiding unexpected errors. Specifically, StrictNodes 0 tells Tor
that it is okay to use an excluded node when it is necessary to perform
relay reachability self-tests, connect to a hidden service, provide a
hidden service to a client, fulfill a .exit request, upload directory
information, or download directory information. (Default: 0)

FascistFirewall0|1

If 1, Tor will only create outgoing connections to ORs running on ports
that your firewall allows (defaults to 80 and 443; see FirewallPorts).
This will allow you to run Tor as a client behind a firewall with
restrictive policies, but will not allow you to run as a server behind such
a firewall. If you prefer more fine-grained control, use
ReachableAddresses instead.

FirewallPortsPORTS

A list of ports that your firewall allows you to connect to. Only used when
FascistFirewall is set. This option is deprecated; use ReachableAddresses
instead. (Default: 80, 443)

Like ReachableAddresses, a list of addresses and ports. Tor will obey
these restrictions when fetching directory information, using standard HTTP
GET requests. If not set explicitly then the value of
ReachableAddresses is used. If HTTPProxy is set then these
connections will go through that proxy. (DEPRECATED: This option has
had no effect for some time.)

ReachableORAddressesIP&lsqb;/MASK]&lsqb;:PORT]…

Like ReachableAddresses, a list of addresses and ports. Tor will obey
these restrictions when connecting to Onion Routers, using TLS/SSL. If not
set explicitly then the value of ReachableAddresses is used. If
HTTPSProxy is set then these connections will go through that proxy.

The separation between ReachableORAddresses and
ReachableDirAddresses is only interesting when you are connecting
through proxies (see HTTPProxy and HTTPSProxy). Most proxies limit
TLS connections (which Tor uses to connect to Onion Routers) to port 443,
and some limit HTTP GET requests (which Tor uses for fetching directory
information) to port 80.

HidServAuthonion-addressauth-cookie &lsqb;service-name]

Client authorization for a hidden service. Valid onion addresses contain 16
characters in a-z2-7 plus ".onion", and valid auth cookies contain 22
characters in A-Za-z0-9+/. The service name is only used for internal
purposes, e.g., for Tor controllers. This option may be used multiple times
for different hidden services. If a hidden service uses authorization and
this option is not set, the hidden service is not accessible. Hidden
services can be configured to require authorization using the
HiddenServiceAuthorizeClient option.

LongLivedPortsPORTS

A list of ports for services that tend to have long-running connections
(e.g. chat and interactive shells). Circuits for streams that use these
ports will contain only high-uptime nodes, to reduce the chance that a node
will go down before the stream is finished. Note that the list is also
honored for circuits (both client and service side) involving hidden
services whose virtual port is in this list. (Default: 21, 22, 706,
1863, 5050, 5190, 5222, 5223, 6523, 6667, 6697, 8300)

MapAddressaddressnewaddress

When a request for address arrives to Tor, it will transform to newaddress
before processing it. For example, if you always want connections to
www.example.com to exit via torserver (where torserver is the
fingerprint of the server), use "MapAddress www.example.com
www.example.com.torserver.exit". If the value is prefixed with a
"*.", matches an entire domain. For example, if you
always want connections to example.com and any if its subdomains
to exit via
torserver (where torserver is the fingerprint of the server), use
"MapAddress *.example.com *.example.com.torserver.exit". (Note the
leading "*." in each part of the directive.) You can also redirect all
subdomains of a domain to a single address. For example, "MapAddress
*.example.com www.example.com".

NOTES:

When evaluating MapAddress expressions Tor stops when it hits the most
recently added expression that matches the requested address. So if you
have the following in your torrc, www.torproject.org will map to 1.1.1.1:

Tor evaluates the MapAddress configuration until it finds no matches. So
if you have the following in your torrc, www.torproject.org will map to
2.2.2.2:

MapAddress 1.1.1.1 2.2.2.2
MapAddress www.torproject.org 1.1.1.1

The following MapAddress expression is invalid (and will be
ignored) because you cannot map from a specific address to a wildcard
address:

MapAddress www.torproject.org *.torproject.org.torserver.exit

Using a wildcard to match only part of a string (as in *ample.com) is
also invalid.

NewCircuitPeriodNUM

Every NUM seconds consider whether to build a new circuit. (Default: 30
seconds)

MaxCircuitDirtinessNUM

Feel free to reuse a circuit that was first used at most NUM seconds ago,
but never attach a new stream to a circuit that is too old. For hidden
services, this applies to the last time a circuit was used, not the
first. Circuits with streams constructed with SOCKS authentication via
SocksPorts that have KeepAliveIsolateSOCKSAuth also remain alive
for MaxCircuitDirtiness seconds after carrying the last such stream.
(Default: 10 minutes)

MaxClientCircuitsPendingNUM

Do not allow more than NUM circuits to be pending at a time for handling
client streams. A circuit is pending if we have begun constructing it,
but it has not yet been completely constructed. (Default: 32)

NodeFamilynode,node,…

The Tor servers, defined by their identity fingerprints,
constitute a "family" of similar or co-administered servers, so never use
any two of them in the same circuit. Defining a NodeFamily is only needed
when a server doesn’t list the family itself (with MyFamily). This option
can be used multiple times; each instance defines a separate family. In
addition to nodes, you can also list IP address and ranges and country
codes in {curly braces}. See the ExcludeNodes option for more
information on how to specify nodes.

EnforceDistinctSubnets0|1

If 1, Tor will not put two servers whose IP addresses are "too close" on
the same circuit. Currently, two addresses are "too close" if they lie in
the same /16 range. (Default: 1)

Open this port to listen for connections from SOCKS-speaking
applications. Set this to 0 if you don’t want to allow application
connections via SOCKS. Set it to "auto" to have Tor pick a port for
you. This directive can be specified multiple times to bind
to multiple addresses/ports. If a unix domain socket is used, you may
quote the path using standard C escape sequences.
(Default: 9050)

NOTE: Although this option allows you to specify an IP address
other than localhost, you should do so only with extreme caution.
The SOCKS protocol is unencrypted and (as we use it)
unauthenticated, so exposing it in this way could leak your
information to anybody watching your network, and allow anybody
to use your computer as an open proxy.

The isolation flags arguments give Tor rules for which streams
received on this SocksPort are allowed to share circuits with one
another. Recognized isolation flags are:

IsolateClientAddr

Don’t share circuits with streams from a different
client address. (On by default and strongly recommended when
supported; you can disable it with NoIsolateClientAddr.
Unsupported and force-disabled when using Unix domain sockets.)

IsolateSOCKSAuth

Don’t share circuits with streams for which different
SOCKS authentication was provided. (For HTTPTunnelPort
connections, this option looks at the Proxy-Authorization and
X-Tor-Stream-Isolation headers. On by default;
you can disable it with NoIsolateSOCKSAuth.)

IsolateClientProtocol

Don’t share circuits with streams using a different protocol.
(SOCKS 4, SOCKS 5, TransPort connections, NATDPort connections,
and DNSPort requests are all considered to be different protocols.)

IsolateDestPort

Don’t share circuits with streams targeting a different
destination port.

IsolateDestAddr

Don’t share circuits with streams targeting a different
destination address.

KeepAliveIsolateSOCKSAuth

If IsolateSOCKSAuth is enabled, keep alive circuits while they have
at least one stream with SOCKS authentication active. After such a circuit
is idle for more than MaxCircuitDirtiness seconds, it can be closed.

SessionGroup=INT

If no other isolation rules would prevent it, allow streams
on this port to share circuits with streams from every other
port with the same session group. (By default, streams received
on different SocksPorts, TransPorts, etc are always isolated from one
another. This option overrides that behavior.)

Other recognized flags for a SocksPort are:

NoIPv4Traffic

Tell exits to not connect to IPv4 addresses in response to SOCKS
requests on this connection.

IPv6Traffic

Tell exits to allow IPv6 addresses in response to SOCKS requests on
this connection, so long as SOCKS5 is in use. (SOCKS4 can’t handle
IPv6.)

PreferIPv6

Tells exits that, if a host has both an IPv4 and an IPv6 address,
we would prefer to connect to it via IPv6. (IPv4 is the default.)

NoDNSRequest

Do not ask exits to resolve DNS addresses in SOCKS5 requests. Tor will
connect to IPv4 addresses, IPv6 addresses (if IPv6Traffic is set) and
.onion addresses.

NoOnionTraffic

Do not connect to .onion addresses in SOCKS5 requests.

OnionTrafficOnly

Tell the tor client to only connect to .onion addresses in response to
SOCKS5 requests on this connection. This is equivalent to NoDNSRequest,
NoIPv4Traffic, NoIPv6Traffic. The corresponding NoOnionTrafficOnly
flag is not supported.

CacheIPv4DNS

Tells the client to remember IPv4 DNS answers we receive from exit
nodes via this connection. (On by default.)

CacheIPv6DNS

Tells the client to remember IPv6 DNS answers we receive from exit
nodes via this connection.

GroupWritable

Unix domain sockets only: makes the socket get created as
group-writable.

WorldWritable

Unix domain sockets only: makes the socket get created as
world-writable.

CacheDNS

Tells the client to remember all DNS answers we receive from exit
nodes via this connection.

UseIPv4Cache

Tells the client to use any cached IPv4 DNS answers we have when making
requests via this connection. (NOTE: This option, along UseIPv6Cache
and UseDNSCache, can harm your anonymity, and probably
won’t help performance as much as you might expect. Use with care!)

UseIPv6Cache

Tells the client to use any cached IPv6 DNS answers we have when making
requests via this connection.

UseDNSCache

Tells the client to use any cached DNS answers we have when making
requests via this connection.

PreferIPv6Automap

When serving a hostname lookup request on this port that
should get automapped (according to AutomapHostsOnResolve),
if we could return either an IPv4 or an IPv6 answer, prefer
an IPv6 answer. (On by default.)

PreferSOCKSNoAuth

Ordinarily, when an application offers both "username/password
authentication" and "no authentication" to Tor via SOCKS5, Tor
selects username/password authentication so that IsolateSOCKSAuth can
work. This can confuse some applications, if they offer a
username/password combination then get confused when asked for
one. You can disable this behavior, so that Tor will select "No
authentication" when IsolateSOCKSAuth is disabled, or when this
option is set.

Flags are processed left to right. If flags conflict, the last flag on the
line is used, and all earlier flags are ignored. No error is issued for
conflicting flags.

SocksPolicypolicy,policy,…

Set an entrance policy for this server, to limit who can connect to the
SocksPort and DNSPort ports. The policies have the same form as exit
policies below, except that port specifiers are ignored. Any address
not matched by some entry in the policy is accepted.

Set the refill interval of Tor’s token bucket to NUM milliseconds.
NUM must be between 1 and 1000, inclusive. Note that the configured
bandwidth limits are still expressed in bytes per second: this
option only affects the frequency with which Tor checks to see whether
previously exhausted connections may read again.
Can not be changed while tor is running. (Default: 100 msec)

TrackHostExitshost,.domain,…

For each value in the comma separated list, Tor will track recent
connections to hosts that match this value and attempt to reuse the same
exit node for each. If the value is prepended with a '.', it is treated as
matching an entire domain. If one of the values is just a '.', it means
match everything. This option is useful if you frequently connect to sites
that will expire all your authentication cookies (i.e. log you out) if
your IP address changes. Note that this option does have the disadvantage
of making it more clear that a given history is associated with a single
user. However, most people who would wish to observe this will observe it
through cookies or other protocol-specific means anyhow.

TrackHostExitsExpireNUM

Since exit servers go up and down, it is desirable to expire the
association between host and exit server after NUM seconds. The default is
1800 seconds (30 minutes).

UpdateBridgesFromAuthority0|1

When set (along with UseBridges), Tor will try to fetch bridge descriptors
from the configured bridge authorities when feasible. It will fall back to
a direct request if the authority responds with a 404. (Default: 0)

UseBridges0|1

When set, Tor will fetch descriptors for each bridge listed in the "Bridge"
config lines, and use these relays as both entry guards and directory
guards. (Default: 0)

UseEntryGuards0|1

If this option is set to 1, we pick a few long-term entry servers, and try
to stick with them. This is desirable because constantly changing servers
increases the odds that an adversary who owns some servers will observe a
fraction of your paths. Entry Guards can not be used by Directory
Authorities, Single Onion Services, and Tor2web clients. In these cases,
the this option is ignored. (Default: 1)

GuardfractionFileFILENAME

V3 authoritative directories only. Configures the location of the
guardfraction file which contains information about how long relays
have been guards. (Default: unset)

UseGuardFraction0|1|auto

This torrc option specifies whether clients should use the
guardfraction information found in the consensus during path
selection. If it’s set to auto, clients will do what the
UseGuardFraction consensus parameter tells them to do. (Default: auto)

NumEntryGuardsNUM

If UseEntryGuards is set to 1, we will try to pick a total of NUM routers
as long-term entries for our circuits. If NUM is 0, we try to learn the
number from the guard-n-primary-guards-to-use consensus parameter, and
default to 1 if the consensus parameter isn’t set. (Default: 0)

NumDirectoryGuardsNUM

If UseEntryGuards is set to 1, we try to make sure we have at least NUM
routers to use as directory guards. If this option is set to 0, use the
value from the guard-n-primary-dir-guards-to-use consensus parameter, and
default to 3 if the consensus parameter isn’t set. (Default: 0)

GuardLifetimeNdays|weeks|months

If nonzero, and UseEntryGuards is set, minimum time to keep a guard before
picking a new one. If zero, we use the GuardLifetime parameter from the
consensus directory. No value here may be less than 1 month or greater
than 5 years; out-of-range values are clamped. (Default: 0)

SafeSocks0|1

When this option is enabled, Tor will reject application connections that
use unsafe variants of the socks protocol — ones that only provide an IP
address, meaning the application is doing a DNS resolve first.
Specifically, these are socks4 and socks5 when not doing remote DNS.
(Default: 0)

TestSocks0|1

When this option is enabled, Tor will make a notice-level log entry for
each connection to the Socks port indicating whether the request used a
safe socks protocol or an unsafe one (see above entry on SafeSocks). This
helps to determine whether an application using Tor is possibly leaking
DNS requests. (Default: 0)

VirtualAddrNetworkIPv4IPv4Address/bits

VirtualAddrNetworkIPv6 &lsqb;IPv6Address]/bits

When Tor needs to assign a virtual (unused) address because of a MAPADDRESS
command from the controller or the AutomapHostsOnResolve feature, Tor
picks an unassigned address from this range. (Defaults:
127.192.0.0/10 and &lsqb;FE80::]/10 respectively.)

When providing proxy server service to a network of computers using a tool
like dns-proxy-tor, change the IPv4 network to "10.192.0.0/10" or
"172.16.0.0/12" and change the IPv6 network to "&lsqb;FC00::]/7".
The default VirtualAddrNetwork address ranges on a
properly configured machine will route to the loopback or link-local
interface. The maximum number of bits for the network prefix is set to 104
for IPv6 and 16 for IPv4. However, a wider network - smaller prefix length

is preferable since it reduces the chances for an attacker to guess the
used IP. For local use, no change to the default VirtualAddrNetwork setting
is needed.

AllowNonRFC953Hostnames0|1

When this option is disabled, Tor blocks hostnames containing illegal
characters (like @ and :) rather than sending them to an exit node to be
resolved. This helps trap accidental attempts to resolve URLs and so on.
(Default: 0)

HTTPTunnelPort &lsqb;address:]port|auto &lsqb;isolation flags]

Open this port to listen for proxy connections using the "HTTP CONNECT"
protocol instead of SOCKS. Set this to 0
0 if you don’t want to allow "HTTP CONNECT" connections. Set the port
to "auto" to have Tor pick a port for you. This directive can be
specified multiple times to bind to multiple addresses/ports. See
SOCKSPort for an explanation of isolation flags. (Default: 0)

TransPort &lsqb;address:]port|auto &lsqb;isolation flags]

Open this port to listen for transparent proxy connections. Set this to
0 if you don’t want to allow transparent proxy connections. Set the port
to "auto" to have Tor pick a port for you. This directive can be
specified multiple times to bind to multiple addresses/ports. See
SOCKSPort for an explanation of isolation flags.

TransPort requires OS support for transparent proxies, such as BSDs' pf or
Linux’s IPTables. If you’re planning to use Tor as a transparent proxy for
a network, you’ll want to examine and change VirtualAddrNetwork from the
default setting. (Default: 0)

TransProxyTypedefault|TPROXY|ipfw|pf-divert

TransProxyType may only be enabled when there is transparent proxy listener
enabled.

Set this to "TPROXY" if you wish to be able to use the TPROXY Linux module
to transparently proxy connections that are configured using the TransPort
option. Detailed information on how to configure the TPROXY
feature can be found in the Linux kernel source tree in the file
Documentation/networking/tproxy.txt.

Set this option to "ipfw" to use the FreeBSD ipfw interface.

On *BSD operating systems when using pf, set this to "pf-divert" to take
advantage of divert-to rules, which do not modify the packets like
rdr-to rules do. Detailed information on how to configure pf to use
divert-to rules can be found in the pf.conf(5) manual page. On OpenBSD,
divert-to is available to use on versions greater than or equal to
OpenBSD 4.4.

Set this to "default", or leave it unconfigured, to use regular IPTables
on Linux, or to use pf rdr-to rules on *BSD systems.

(Default: "default".)

NATDPort &lsqb;address:]port|auto &lsqb;isolation flags]

Open this port to listen for connections from old versions of ipfw (as
included in old versions of FreeBSD, etc) using the NATD protocol.
Use 0 if you don’t want to allow NATD connections. Set the port
to "auto" to have Tor pick a port for you. This directive can be
specified multiple times to bind to multiple addresses/ports. See
SocksPort for an explanation of isolation flags.

This option is only for people who cannot use TransPort. (Default: 0)

AutomapHostsOnResolve0|1

When this option is enabled, and we get a request to resolve an address
that ends with one of the suffixes in AutomapHostsSuffixes, we map an
unused virtual address to that address, and return the new virtual address.
This is handy for making ".onion" addresses work with applications that
resolve an address and then connect to it. (Default: 0)

AutomapHostsSuffixesSUFFIX,SUFFIX,…

A comma-separated list of suffixes to use with AutomapHostsOnResolve.
The "." suffix is equivalent to "all addresses." (Default: .exit,.onion).

DNSPort &lsqb;address:]port|auto &lsqb;isolation flags]

If non-zero, open this port to listen for UDP DNS requests, and resolve
them anonymously. This port only handles A, AAAA, and PTR requests---it
doesn’t handle arbitrary DNS request types. Set the port to "auto" to
have Tor pick a port for
you. This directive can be specified multiple times to bind to multiple
addresses/ports. See SocksPort for an explanation of isolation
flags. (Default: 0)

ClientDNSRejectInternalAddresses0|1

If true, Tor does not believe any anonymously retrieved DNS answer that
tells it that an address resolves to an internal address (like 127.0.0.1 or
192.168.0.1). This option prevents certain browser-based attacks; it
is not allowed to be set on the default network. (Default: 1)

ClientRejectInternalAddresses0|1

If true, Tor does not try to fulfill requests to connect to an internal
address (like 127.0.0.1 or 192.168.0.1) unless an exit node is
specifically requested (for example, via a .exit hostname, or a
controller request). If true, multicast DNS hostnames for machines on the
local network (of the form *.local) are also rejected. (Default: 1)

DownloadExtraInfo0|1

If true, Tor downloads and caches "extra-info" documents. These documents
contain information about servers other than the information in their
regular server descriptors. Tor does not use this information for anything
itself; to save bandwidth, leave this option turned off. (Default: 0)

WarnPlaintextPortsport,port,…

Tells Tor to issue a warnings whenever the user tries to make an anonymous
connection to one of these ports. This option is designed to alert users
to services that risk sending passwords in the clear. (Default:
23,109,110,143)

RejectPlaintextPortsport,port,…

Like WarnPlaintextPorts, but instead of warning about risky port uses, Tor
will instead refuse to make the connection. (Default: None)

OptimisticData0|1|auto

When this option is set, and Tor is using an exit node that supports
the feature, it will try optimistically to send data to the exit node
without waiting for the exit node to report whether the connection
succeeded. This can save a round-trip time for protocols like HTTP
where the client talks first. If OptimisticData is set to auto,
Tor will look at the UseOptimisticData parameter in the networkstatus.
(Default: auto)

Tor2webMode0|1

When this option is set, Tor connects to hidden services
non-anonymously. This option also disables client connections to
non-hidden-service hostnames through Tor. It must only be used when
running a tor2web Hidden Service web proxy.
To enable this option the compile time flag --enable-tor2web-mode must be
specified. Since Tor2webMode is non-anonymous, you can not run an
anonymous Hidden Service on a tor version compiled with Tor2webMode.
(Default: 0)

Tor2webRendezvousPointsnode,node,…

A list of identity fingerprints, nicknames, country codes and
address patterns of nodes that are allowed to be used as RPs
in HS circuits; any other nodes will not be used as RPs.
(Example:
Tor2webRendezvousPoints Fastyfasty, ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc}, 255.254.0.0/8)

This feature can only be used if Tor2webMode is also enabled.

ExcludeNodes have higher priority than Tor2webRendezvousPoints,
which means that nodes specified in ExcludeNodes will not be
picked as RPs.

If no nodes in Tor2webRendezvousPoints are currently available for
use, Tor will choose a random node when building HS circuits.

UseMicrodescriptors0|1|auto

Microdescriptors are a smaller version of the information that Tor needs
in order to build its circuits. Using microdescriptors makes Tor clients
download less directory information, thus saving bandwidth. Directory
caches need to fetch regular descriptors and microdescriptors, so this
option doesn’t save any bandwidth for them. If this option is set to
"auto" (recommended) then it is on for all clients that do not set
FetchUselessDescriptors. (Default: auto)

PathBiasCircThresholdNUM

PathBiasNoticeRateNUM

PathBiasWarnRateNUM

PathBiasExtremeRateNUM

PathBiasDropGuardsNUM

PathBiasScaleThresholdNUM

These options override the default behavior of Tor’s (currently
experimental) path bias detection algorithm. To try to find broken or
misbehaving guard nodes, Tor looks for nodes where more than a certain
fraction of circuits through that guard fail to get built.

The PathBiasCircThreshold option controls how many circuits we need to build
through a guard before we make these checks. The PathBiasNoticeRate,
PathBiasWarnRate and PathBiasExtremeRate options control what fraction of
circuits must succeed through a guard so we won’t write log messages.
If less than PathBiasExtremeRate circuits succeed and PathBiasDropGuards
is set to 1, we disable use of that guard.

When we have seen more than PathBiasScaleThreshold
circuits through a guard, we scale our observations by 0.5 (governed by
the consensus) so that new observations don’t get swamped by old ones.

By default, or if a negative value is provided for one of these options,
Tor uses reasonable defaults from the networkstatus consensus document.
If no defaults are available there, these options default to 150, .70,
.50, .30, 0, and 300 respectively.

PathBiasUseThresholdNUM

PathBiasNoticeUseRateNUM

PathBiasExtremeUseRateNUM

PathBiasScaleUseThresholdNUM

Similar to the above options, these options override the default behavior
of Tor’s (currently experimental) path use bias detection algorithm.

Where as the path bias parameters govern thresholds for successfully
building circuits, these four path use bias parameters govern thresholds
only for circuit usage. Circuits which receive no stream usage
are not counted by this detection algorithm. A used circuit is considered
successful if it is capable of carrying streams or otherwise receiving
well-formed responses to RELAY cells.

By default, or if a negative value is provided for one of these options,
Tor uses reasonable defaults from the networkstatus consensus document.
If no defaults are available there, these options default to 20, .80,
.60, and 100, respectively.

ClientUseIPv40|1

If this option is set to 0, Tor will avoid connecting to directory servers
and entry nodes over IPv4. Note that clients with an IPv4
address in a Bridge, proxy, or pluggable transport line will try
connecting over IPv4 even if ClientUseIPv4 is set to 0. (Default: 1)

ClientUseIPv60|1

If this option is set to 1, Tor might connect to directory servers or
entry nodes over IPv6. Note that clients configured with an IPv6 address
in a Bridge, proxy, or pluggable transport line will try connecting
over IPv6 even if ClientUseIPv6 is set to 0. (Default: 0)

ClientPreferIPv6DirPort0|1|auto

If this option is set to 1, Tor prefers a directory port with an IPv6
address over one with IPv4, for direct connections, if a given directory
server has both. (Tor also prefers an IPv6 DirPort if IPv4Client is set to
0.) If this option is set to auto, clients prefer IPv4. Other things may
influence the choice. This option breaks a tie to the favor of IPv6.
(Default: auto) (DEPRECATED: This option has had no effect for some
time.)

ClientPreferIPv6ORPort0|1|auto

If this option is set to 1, Tor prefers an OR port with an IPv6
address over one with IPv4 if a given entry node has both. (Tor also
prefers an IPv6 ORPort if IPv4Client is set to 0.) If this option is set
to auto, Tor bridge clients prefer the configured bridge address, and
other clients prefer IPv4. Other things may influence the choice. This
option breaks a tie to the favor of IPv6. (Default: auto)

PathsNeededToBuildCircuitsNUM

Tor clients don’t build circuits for user traffic until they know
about enough of the network so that they could potentially construct
enough of the possible paths through the network. If this option
is set to a fraction between 0.25 and 0.95, Tor won’t build circuits
until it has enough descriptors or microdescriptors to construct
that fraction of possible paths. Note that setting this option too low
can make your Tor client less anonymous, and setting it too high can
prevent your Tor client from bootstrapping. If this option is negative,
Tor will use a default value chosen by the directory authorities. If the
directory authorities do not choose a value, Tor will default to 0.6.
(Default: -1.)

ClientBootstrapConsensusAuthorityDownloadScheduleN,N,…

Schedule for when clients should download consensuses from authorities
if they are bootstrapping (that is, they don’t have a usable, reasonably
live consensus). Only used by clients fetching from a list of fallback
directory mirrors. This schedule is advanced by (potentially concurrent)
connection attempts, unlike other schedules, which are advanced by
connection failures. (Default: 6, 11, 3600, 10800, 25200, 54000, 111600,
262800)

ClientBootstrapConsensusFallbackDownloadScheduleN,N,…

Schedule for when clients should download consensuses from fallback
directory mirrors if they are bootstrapping (that is, they don’t have a
usable, reasonably live consensus). Only used by clients fetching from a
list of fallback directory mirrors. This schedule is advanced by
(potentially concurrent) connection attempts, unlike other schedules,
which are advanced by connection failures. (Default: 0, 1, 4, 11, 3600,
10800, 25200, 54000, 111600, 262800)

ClientBootstrapConsensusAuthorityOnlyDownloadScheduleN,N,…

Schedule for when clients should download consensuses from authorities
if they are bootstrapping (that is, they don’t have a usable, reasonably
live consensus). Only used by clients which don’t have or won’t fetch
from a list of fallback directory mirrors. This schedule is advanced by
(potentially concurrent) connection attempts, unlike other schedules,
which are advanced by connection failures. (Default: 0, 3, 7, 3600,
10800, 25200, 54000, 111600, 262800)

ClientBootstrapConsensusMaxDownloadTriesNUM

Try this many times to download a consensus while bootstrapping using
fallback directory mirrors before giving up. (Default: 7)

ClientBootstrapConsensusAuthorityOnlyMaxDownloadTriesNUM

Try this many times to download a consensus while bootstrapping using
authorities before giving up. (Default: 4)

ClientBootstrapConsensusMaxInProgressTriesNUM

Try this many simultaneous connections to download a consensus before
waiting for one to complete, timeout, or error out. (Default: 3)

SERVER OPTIONS

The following options are useful only for servers (that is, if ORPort
is non-zero):

Addressaddress

The IPv4 address of this server, or a fully qualified domain name of
this server that resolves to an IPv4 address. You can leave this
unset, and Tor will try to guess your IPv4 address. This IPv4
address is the one used to tell clients and other servers where to
find your Tor server; it doesn’t affect the address that your server
binds to. To bind to a different address, use the ORPort and
OutboundBindAddress options.

AssumeReachable0|1

This option is used when bootstrapping a new Tor network. If set to 1,
don’t do self-reachability testing; just upload your server descriptor
immediately. If AuthoritativeDirectory is also set, this option
instructs the dirserver to bypass remote reachability testing too and list
all connected servers as running.

BridgeRelay0|1

Sets the relay to act as a "bridge" with respect to relaying connections
from bridge users to the Tor network. It mainly causes Tor to publish a
server descriptor to the bridge database, rather than
to the public directory authorities.

BridgeDistributionstring

If set along with BridgeRelay, Tor will include a new line in its
bridge descriptor which indicates to the BridgeDB service how it
would like its bridge address to be given out. Set it to "none" if
you want BridgeDB to avoid distributing your bridge address, or "any" to
let BridgeDB decide. (Default: any)
Note: as of Oct 2017, the BridgeDB part of this option is not yet
implemented. Until BridgeDB is updated to obey this option, your
bridge will make this request, but it will not (yet) be obeyed.

ContactInfoemail_address

Administrative contact information for this relay or bridge. This line
can be used to contact you if your relay or bridge is misconfigured or
something else goes wrong. Note that we archive and publish all
descriptors containing these lines and that Google indexes them, so
spammers might also collect them. You may want to obscure the fact
that it’s an email address and/or generate a new address for this
purpose.

ExitRelay0|1|auto

Tells Tor whether to run as an exit relay. If Tor is running as a
non-bridge server, and ExitRelay is set to 1, then Tor allows traffic to
exit according to the ExitPolicy option (or the default ExitPolicy if
none is specified).

If ExitRelay is set to 0, no traffic is allowed to
exit, and the ExitPolicy option is ignored.

If ExitRelay is set to "auto", then Tor behaves as if it were set to 1, but
warns the user if this would cause traffic to exit. In a future version,
the default value will be 0. (Default: auto)

ExitPolicypolicy,policy,…

Set an exit policy for this server. Each policy is of the form
"accept&lsqb;6]|reject&lsqb;6]ADDR&lsqb;/MASK]&lsqb;:PORT]". If /MASK is
omitted then this policy just applies to the host given. Instead of giving
a host or network you can also use "*" to denote the universe (0.0.0.0/0
and ::/128), or *4 to denote all IPv4 addresses, and *6 to denote all
IPv6 addresses.
PORT can be a single port number, an interval of ports
"FROM_PORT-TO_PORT", or "*". If PORT is omitted, that means
"*".

For example, "accept 18.7.22.69:*,reject 18.0.0.0/8:*,accept *:*" would
reject any IPv4 traffic destined for MIT except for web.mit.edu, and accept
any other IPv4 or IPv6 traffic.

accept6 and reject6 only produce IPv6 exit policy entries. Using an IPv4
address with accept6 or reject6 is ignored and generates a warning.
accept/reject allows either IPv4 or IPv6 addresses. Use *4 as an IPv4
wildcard address, and *6 as an IPv6 wildcard address. accept/reject *
expands to matching IPv4 and IPv6 wildcard address rules.

To specify all IPv4 and IPv6 internal and link-local networks (including
0.0.0.0/8, 169.254.0.0/16, 127.0.0.0/8, 192.168.0.0/16, 10.0.0.0/8,
172.16.0.0/12, &lsqb;::]/8, &lsqb;FC00::]/7, &lsqb;FE80::]/10, &lsqb;FEC0::]/10, &lsqb;FF00::]/8,
and &lsqb;::]/127), you can use the "private" alias instead of an address.
("private" always produces rules for IPv4 and IPv6 addresses, even when
used with accept6/reject6.)

Private addresses are rejected by default (at the beginning of your exit
policy), along with any configured primary public IPv4 and IPv6 addresses.
These private addresses are rejected unless you set the
ExitPolicyRejectPrivate config option to 0. For example, once you’ve done
that, you could allow HTTP to 127.0.0.1 and block all other connections to
internal networks with "accept 127.0.0.1:80,reject private:*", though that
may also allow connections to your own computer that are addressed to its
public (external) IP address. See RFC 1918 and RFC 3330 for more details
about internal and reserved IP address space. See
ExitPolicyRejectLocalInterfaces if you want to block every address on the
relay, even those that aren’t advertised in the descriptor.

This directive can be specified multiple times so you don’t have to put it
all on one line.

Policies are considered first to last, and the first match wins. If you
want to allow the same ports on IPv4 and IPv6, write your rules using
accept/reject *. If you want to allow different ports on IPv4 and IPv6,
write your IPv6 rules using accept6/reject6 *6, and your IPv4 rules using
accept/reject *4. If you want to _replace_ the default exit policy, end
your exit policy with either a reject *:* or an accept *:*. Otherwise,
you’re _augmenting_ (prepending to) the default exit policy. The default
exit policy is:

Since the default exit policy uses accept/reject *, it applies to both
IPv4 and IPv6 addresses.

ExitPolicyRejectPrivate0|1

Reject all private (local) networks, along with the relay’s advertised
public IPv4 and IPv6 addresses, at the beginning of your exit policy.
See above entry on ExitPolicy.
(Default: 1)

ExitPolicyRejectLocalInterfaces0|1

Reject all IPv4 and IPv6 addresses that the relay knows about, at the
beginning of your exit policy. This includes any OutboundBindAddress, the
bind addresses of any port options, such as ControlPort or DNSPort, and any
public IPv4 and IPv6 addresses on any interface on the relay. (If IPv6Exit
is not set, all IPv6 addresses will be rejected anyway.)
See above entry on ExitPolicy.
This option is off by default, because it lists all public relay IP
addresses in the ExitPolicy, even those relay operators might prefer not
to disclose.
(Default: 0)

IPv6Exit0|1

If set, and we are an exit node, allow clients to use us for IPv6
traffic. (Default: 0)

MaxOnionQueueDelayNUM &lsqb;msec|second]

If we have more onionskins queued for processing than we can process in
this amount of time, reject new ones. (Default: 1750 msec)

MyFamilyfingerprint,fingerprint,…

Declare that this Tor relay is controlled or administered by a group or
organization identical or similar to that of the other relays, defined by
their (possibly $-prefixed) identity fingerprints.
This option can be repeated many times, for
convenience in defining large families: all fingerprints in all MyFamily
lines are merged into one list.
When two relays both declare that they are in the
same 'family', Tor clients will not use them in the same circuit. (Each
relay only needs to list the other servers in its family; it doesn’t need to
list itself, but it won’t hurt if it does.) Do not list any bridge relay as it would
compromise its concealment.

When listing a node, it’s better to list it by fingerprint than by
nickname: fingerprints are more reliable.

Nicknamename

Set the server’s nickname to 'name'. Nicknames must be between 1 and 19
characters inclusive, and must contain only the characters &lsqb;a-zA-Z0-9].

NumCPUsnum

How many processes to use at once for decrypting onionskins and other
parallelizable operations. If this is set to 0, Tor will try to detect
how many CPUs you have, defaulting to 1 if it can’t tell. (Default: 0)

ORPort &lsqb;address:]PORT|auto &lsqb;flags]

Advertise this port to listen for connections from Tor clients and
servers. This option is required to be a Tor server.
Set it to "auto" to have Tor pick a port for you. Set it to 0 to not
run an ORPort at all. This option can occur more than once. (Default: 0)

Tor recognizes these flags on each ORPort:

NoAdvertise

By default, we bind to a port and tell our users about it. If
NoAdvertise is specified, we don’t advertise, but listen anyway. This
can be useful if the port everybody will be connecting to (for
example, one that’s opened on our firewall) is somewhere else.

NoListen

By default, we bind to a port and tell our users about it. If
NoListen is specified, we don’t bind, but advertise anyway. This
can be useful if something else (for example, a firewall’s port
forwarding configuration) is causing connections to reach us.

IPv4Only

If the address is absent, or resolves to both an IPv4 and an IPv6
address, only listen to the IPv4 address.

IPv6Only

If the address is absent, or resolves to both an IPv4 and an IPv6
address, only listen to the IPv6 address.

For obvious reasons, NoAdvertise and NoListen are mutually exclusive, and
IPv4Only and IPv6Only are mutually exclusive.

PortForwarding0|1

Attempt to automatically forward the DirPort and ORPort on a NAT router
connecting this Tor server to the Internet. If set, Tor will try both
NAT-PMP (common on Apple routers) and UPnP (common on routers from other
manufacturers). (Default: 0)

PortForwardingHelperfilename|pathname

If PortForwarding is set, use this executable to configure the forwarding.
If set to a filename, the system path will be searched for the executable.
If set to a path, only the specified path will be executed.
(Default: tor-fw-helper)

PublishServerDescriptor0|1|v3|bridge,…

This option specifies which descriptors Tor will publish when acting as
a relay. You can
choose multiple arguments, separated by commas.

If this option is set to 0, Tor will not publish its
descriptors to any directories. (This is useful if you’re testing
out your server, or if you’re using a Tor controller that handles
directory publishing for you.) Otherwise, Tor will publish its
descriptors of all type(s) specified. The default is "1", which
means "if running as a relay or bridge, publish descriptors to the
appropriate authorities". Other possibilities are "v3", meaning
"publish as if you’re a relay", and "bridge", meaning "publish as
if you’re a bridge".

ShutdownWaitLengthNUM

When we get a SIGINT and we’re a server, we begin shutting down:
we close listeners and start refusing new circuits. After NUM
seconds, we exit. If we get a second SIGINT, we exit immediately.
(Default: 30 seconds)

SSLKeyLifetimeNminutes|hours|days|weeks

When creating a link certificate for our outermost SSL handshake,
set its lifetime to this amount of time. If set to 0, Tor will choose
some reasonable random defaults. (Default: 0)

HeartbeatPeriodNminutes|hours|days|weeks

Log a heartbeat message every HeartbeatPeriod seconds. This is
a log level notice message, designed to let you know your Tor
server is still alive and doing useful things. Settings this
to 0 will disable the heartbeat. Otherwise, it must be at least 30
minutes. (Default: 6 hours)

Limits the max number of bytes sent and received within a set time period
using a given calculation rule (see: AccountingStart, AccountingRule).
Useful if you need to stay under a specific bandwidth. By default, the
number used for calculation is the max of either the bytes sent or
received. For example, with AccountingMax set to 1 GByte, a server
could send 900 MBytes and receive 800 MBytes and continue running.
It will only hibernate once one of the two reaches 1 GByte. This can
be changed to use the sum of the both bytes received and sent by setting
the AccountingRule option to "sum" (total bandwidth in/out). When the
number of bytes remaining gets low, Tor will stop accepting new connections
and circuits. When the number of bytes is exhausted, Tor will hibernate
until some time in the next accounting period. To prevent all servers
from waking at the same time, Tor will also wait until a random point
in each period before waking up. If you have bandwidth cost issues,
enabling hibernation is preferable to setting a low bandwidth, since
it provides users with a collection of fast servers that are up some
of the time, which is more useful than a set of slow servers that are
always "available".

AccountingRulesum|max|in|out

How we determine when our AccountingMax has been reached (when we
should hibernate) during a time interval. Set to "max" to calculate
using the higher of either the sent or received bytes (this is the
default functionality). Set to "sum" to calculate using the sent
plus received bytes. Set to "in" to calculate using only the
received bytes. Set to "out" to calculate using only the sent bytes.
(Default: max)

AccountingStartday|week|month &lsqb;day] HH:MM

Specify how long accounting periods last. If month is given, each
accounting period runs from the time HH:MM on the dayth day of one
month to the same day and time of the next. (The day must be between 1 and
28.) If week is given, each accounting period runs from the time HH:MM
of the dayth day of one week to the same day and time of the next week,
with Monday as day 1 and Sunday as day 7. If day is given, each
accounting period runs from the time HH:MM each day to the same time on
the next day. All times are local, and given in 24-hour time. (Default:
"month 1 0:00")

RefuseUnknownExits0|1|auto

Prevent nodes that don’t appear in the consensus from exiting using this
relay. If the option is 1, we always block exit attempts from such
nodes; if it’s 0, we never do, and if the option is "auto", then we do
whatever the authorities suggest in the consensus (and block if the consensus
is quiet on the issue). (Default: auto)

ServerDNSResolvConfFilefilename

Overrides the default DNS configuration with the configuration in
filename. The file format is the same as the standard Unix
"resolv.conf" file (7). This option, like all other ServerDNS options,
only affects name lookups that your server does on behalf of clients.
(Defaults to use the system DNS configuration.)

ServerDNSAllowBrokenConfig0|1

If this option is false, Tor exits immediately if there are problems
parsing the system DNS configuration or connecting to nameservers.
Otherwise, Tor continues to periodically retry the system nameservers until
it eventually succeeds. (Default: 1)

ServerDNSSearchDomains0|1

If set to 1, then we will search for addresses in the local search domain.
For example, if this system is configured to believe it is in
"example.com", and a client tries to connect to "www", the client will be
connected to "www.example.com". This option only affects name lookups that
your server does on behalf of clients. (Default: 0)

ServerDNSDetectHijacking0|1

When this option is set to 1, we will test periodically to determine
whether our local nameservers have been configured to hijack failing DNS
requests (usually to an advertising site). If they are, we will attempt to
correct this. This option only affects name lookups that your server does
on behalf of clients. (Default: 1)

ServerDNSTestAddresseshostname,hostname,…

When we’re detecting DNS hijacking, make sure that these valid addresses
aren’t getting redirected. If they are, then our DNS is completely useless,
and we’ll reset our exit policy to "reject *:*". This option only affects
name lookups that your server does on behalf of clients. (Default:
"www.google.com, www.mit.edu, www.yahoo.com, www.slashdot.org")

ServerDNSAllowNonRFC953Hostnames0|1

When this option is disabled, Tor does not try to resolve hostnames
containing illegal characters (like @ and :) rather than sending them to an
exit node to be resolved. This helps trap accidental attempts to resolve
URLs and so on. This option only affects name lookups that your server does
on behalf of clients. (Default: 0)

BridgeRecordUsageByCountry0|1

When this option is enabled and BridgeRelay is also enabled, and we have
GeoIP data, Tor keeps a per-country count of how many client
addresses have contacted it so that it can help the bridge authority guess
which countries have blocked access to it. (Default: 1)

ServerDNSRandomizeCase0|1

When this option is set, Tor sets the case of each character randomly in
outgoing DNS requests, and makes sure that the case matches in DNS replies.
This so-called "0x20 hack" helps resist some types of DNS poisoning attack.
For more information, see "Increased DNS Forgery Resistance through
0x20-Bit Encoding". This option only affects name lookups that your server
does on behalf of clients. (Default: 1)

GeoIPFilefilename

A filename containing IPv4 GeoIP data, for use with by-country statistics.

GeoIPv6Filefilename

A filename containing IPv6 GeoIP data, for use with by-country statistics.

CellStatistics0|1

Relays only.
When this option is enabled, Tor collects statistics about cell
processing (i.e. mean time a cell is spending in a queue, mean
number of cells in a queue and mean number of processed cells per
circuit) and writes them into disk every 24 hours. Onion router
operators may use the statistics for performance monitoring.
If ExtraInfoStatistics is enabled, it will published as part of
extra-info document. (Default: 0)

PaddingStatistics0|1

Relays only.
When this option is enabled, Tor collects statistics for padding cells
sent and received by this relay, in addition to total cell counts.
These statistics are rounded, and omitted if traffic is low. This
information is important for load balancing decisions related to padding.
(Default: 1)

DirReqStatistics0|1

Relays and bridges only.
When this option is enabled, a Tor directory writes statistics on the
number and response time of network status requests to disk every 24
hours. Enables relay and bridge operators to monitor how much their
server is being used by clients to learn about Tor network.
If ExtraInfoStatistics is enabled, it will published as part of
extra-info document. (Default: 1)

EntryStatistics0|1

Relays only.
When this option is enabled, Tor writes statistics on the number of
directly connecting clients to disk every 24 hours. Enables relay
operators to monitor how much inbound traffic that originates from
Tor clients passes through their server to go further down the
Tor network. If ExtraInfoStatistics is enabled, it will be published
as part of extra-info document. (Default: 0)

ExitPortStatistics0|1

Exit relays only.
When this option is enabled, Tor writes statistics on the number of
relayed bytes and opened stream per exit port to disk every 24 hours.
Enables exit relay operators to measure and monitor amounts of traffic
that leaves Tor network through their exit node. If ExtraInfoStatistics
is enabled, it will be published as part of extra-info document.
(Default: 0)

ConnDirectionStatistics0|1

Relays only.
When this option is enabled, Tor writes statistics on the amounts of
traffic it passes between itself and other relays to disk every 24
hours. Enables relay operators to monitor how much their relay is
being used as middle node in the circuit. If ExtraInfoStatistics is
enabled, it will be published as part of extra-info document.
(Default: 0)

HiddenServiceStatistics0|1

Relays only.
When this option is enabled, a Tor relay writes obfuscated
statistics on its role as hidden-service directory, introduction
point, or rendezvous point to disk every 24 hours. If
ExtraInfoStatistics is also enabled, these statistics are further
published to the directory authorities. (Default: 1)

ExtraInfoStatistics0|1

When this option is enabled, Tor includes previously gathered statistics in
its extra-info documents that it uploads to the directory authorities.
(Default: 1)

ExtendAllowPrivateAddresses0|1

When this option is enabled, Tor will connect to relays on localhost,
RFC1918 addresses, and so on. In particular, Tor will make direct OR
connections, and Tor routers allow EXTEND requests, to these private
addresses. (Tor will always allow connections to bridges, proxies, and
pluggable transports configured on private addresses.) Enabling this
option can create security issues; you should probably leave it off.
(Default: 0)

MaxMemInQueuesNbytes|KB|MB|GB

This option configures a threshold above which Tor will assume that it
needs to stop queueing or buffering data because it’s about to run out of
memory. If it hits this threshold, it will begin killing circuits until
it has recovered at least 10% of this memory. Do not set this option too
low, or your relay may be unreliable under load. This option only
affects some queues, so the actual process size will be larger than
this. If this option is set to 0, Tor will try to pick a reasonable
default based on your system’s physical memory. (Default: 0)

DisableOOSCheck0|1

This option disables the code that closes connections when Tor notices
that it is running low on sockets. Right now, it is on by default,
since the existing out-of-sockets mechanism tends to kill OR connections
more than it should. (Default: 1)

SigningKeyLifetimeNdays|weeks|months

For how long should each Ed25519 signing key be valid? Tor uses a
permanent master identity key that can be kept offline, and periodically
generates new "signing" keys that it uses online. This option
configures their lifetime.
(Default: 30 days)

OfflineMasterKey0|1

If non-zero, the Tor relay will never generate or load its master secret
key. Instead, you’ll have to use "tor --keygen" to manage the permanent
ed25519 master identity key, as well as the corresponding temporary
signing keys and certificates. (Default: 0)

DIRECTORY SERVER OPTIONS

The following options are useful only for directory servers. (Relays with
enough bandwidth automatically become directory servers; see DirCache for
details.)

DirPortFrontPageFILENAME

When this option is set, it takes an HTML file and publishes it as "/" on
the DirPort. Now relay operators can provide a disclaimer without needing
to set up a separate webserver. There’s a sample disclaimer in
contrib/operator-tools/tor-exit-notice.html.

DirPort &lsqb;address:]PORT|auto &lsqb;flags]

If this option is nonzero, advertise the directory service on this port.
Set it to "auto" to have Tor pick a port for you. This option can occur
more than once, but only one advertised DirPort is supported: all
but one DirPort must have the NoAdvertise flag set. (Default: 0)

The same flags are supported here as are supported by ORPort.

DirPolicypolicy,policy,…

Set an entrance policy for this server, to limit who can connect to the
directory ports. The policies have the same form as exit policies above,
except that port specifiers are ignored. Any address not matched by
some entry in the policy is accepted.

DirCache0|1

When this option is set, Tor caches all current directory documents and
accepts client requests for them. Setting DirPort is not required for this,
because clients connect via the ORPort by default. Setting either DirPort
or BridgeRelay and setting DirCache to 0 is not supported. (Default: 1)

MaxConsensusAgeForDiffsNminutes|hours|days|weeks

When this option is nonzero, Tor caches will not try to generate
consensus diffs for any consensus older than this amount of time.
If this option is set to zero, Tor will pick a reasonable default from
the current networkstatus document. You should not set this
option unless your cache is severely low on disk space or CPU.
If you need to set it, keeping it above 3 or 4 hours will help clients
much more than setting it to zero.
(Default: 0)

DIRECTORY AUTHORITY SERVER OPTIONS

The following options enable operation as a directory authority, and
control how Tor behaves as a directory authority. You should not need
to adjust any of them if you’re running a regular relay or exit server
on the public Tor network.

AuthoritativeDirectory0|1

When this option is set to 1, Tor operates as an authoritative directory
server. Instead of caching the directory, it generates its own list of
good servers, signs it, and sends that to the clients. Unless the clients
already have you listed as a trusted directory, you probably do not want
to set this option.

V3AuthoritativeDirectory0|1

When this option is set in addition to AuthoritativeDirectory, Tor
generates version 3 network statuses and serves descriptors, etc as
described in dir-spec.txt file of torspec
(for Tor clients and servers running at least 0.2.0.x).

VersioningAuthoritativeDirectory0|1

When this option is set to 1, Tor adds information on which versions of
Tor are still believed safe for use to the published directory. Each
version 1 authority is automatically a versioning authority; version 2
authorities provide this service optionally. See RecommendedVersions,
RecommendedClientVersions, and RecommendedServerVersions.

RecommendedVersionsSTRING

STRING is a comma-separated list of Tor versions currently believed to be
safe. The list is included in each directory, and nodes which pull down the
directory learn whether they need to upgrade. This option can appear
multiple times: the values from multiple lines are spliced together. When
this is set then VersioningAuthoritativeDirectory should be set too.

RecommendedPackagesPACKAGENAMEVERSIONURLDIGESTTYPE=DIGEST

Adds "package" line to the directory authority’s vote. This information
is used to vote on the correct URL and digest for the released versions
of different Tor-related packages, so that the consensus can certify
them. This line may appear any number of times.

RecommendedClientVersionsSTRING

STRING is a comma-separated list of Tor versions currently believed to be
safe for clients to use. This information is included in version 2
directories. If this is not set then the value of RecommendedVersions
is used. When this is set then VersioningAuthoritativeDirectory should
be set too.

BridgeAuthoritativeDir0|1

When this option is set in addition to AuthoritativeDirectory, Tor
accepts and serves server descriptors, but it caches and serves the main
networkstatus documents rather than generating its own. (Default: 0)

MinUptimeHidServDirectoryV2Nseconds|minutes|hours|days|weeks

Minimum uptime of a v2 hidden service directory to be accepted as such by
authoritative directories. (Default: 25 hours)

RecommendedServerVersionsSTRING

STRING is a comma-separated list of Tor versions currently believed to be
safe for servers to use. This information is included in version 2
directories. If this is not set then the value of RecommendedVersions
is used. When this is set then VersioningAuthoritativeDirectory should
be set too.

ConsensusParamsSTRING

STRING is a space-separated list of key=value pairs that Tor will include
in the "params" line of its networkstatus vote.

DirAllowPrivateAddresses0|1

If set to 1, Tor will accept server descriptors with arbitrary "Address"
elements. Otherwise, if the address is not an IP address or is a private IP
address, it will reject the server descriptor. Additionally, Tor
will allow exit policies for private networks to fulfill Exit flag
requirements. (Default: 0)

AuthDirBadExitAddressPattern…

Authoritative directories only. A set of address patterns for servers that
will be listed as bad exits in any network status document this authority
publishes, if AuthDirListBadExits is set.

(The address pattern syntax here and in the options below
is the same as for exit policies, except that you don’t need to say
"accept" or "reject", and ports are not needed.)

AuthDirInvalidAddressPattern…

Authoritative directories only. A set of address patterns for servers that
will never be listed as "valid" in any network status document that this
authority publishes.

AuthDirRejectAddressPattern…

Authoritative directories only. A set of address patterns for servers that
will never be listed at all in any network status document that this
authority publishes, or accepted as an OR address in any descriptor
submitted for publication by this authority.

AuthDirBadExitCCsCC,…

AuthDirInvalidCCsCC,…

AuthDirRejectCCsCC,…

Authoritative directories only. These options contain a comma-separated
list of country codes such that any server in one of those country codes
will be marked as a bad exit/invalid for use, or rejected
entirely.

AuthDirListBadExits0|1

Authoritative directories only. If set to 1, this directory has some
opinion about which nodes are unsuitable as exit nodes. (Do not set this to
1 unless you plan to list non-functioning exits as bad; otherwise, you are
effectively voting in favor of every declared exit as an exit.)

AuthDirMaxServersPerAddrNUM

Authoritative directories only. The maximum number of servers that we will
list as acceptable on a single IP address. Set this to "0" for "no limit".
(Default: 2)

Authoritative directories only. If non-zero, this advertised capacity
or more is always sufficient to satisfy the bandwidth requirement
for the Guard flag. (Default: 2 MBytes)

AuthDirPinKeys0|1

Authoritative directories only. If non-zero, do not allow any relay to
publish a descriptor if any other relay has reserved its <Ed25519,RSA>
identity keypair. In all cases, Tor records every keypair it accepts
in a journal if it is new, or if it differs from the most recently
accepted pinning for one of the keys it contains. (Default: 1)

AuthDirSharedRandomness0|1

Authoritative directories only. Switch for the shared random protocol.
If zero, the authority won’t participate in the protocol. If non-zero
(default), the flag "shared-rand-participate" is added to the authority
vote indicating participation in the protocol. (Default: 1)

AuthDirTestEd25519LinkKeys0|1

Authoritative directories only. If this option is set to 0, then we treat
relays as "Running" if their RSA key is correct when we probe them,
regardless of their Ed25519 key. We should only ever set this option to 0
if there is some major bug in Ed25519 link authentication that causes us
to label all the relays as not Running. (Default: 1)

BridgePasswordPassword

If set, contains an HTTP authenticator that tells a bridge authority to
serve all requested bridge information. Used by the (only partially
implemented) "bridge community" design, where a community of bridge
relay operators all use an alternate bridge directory authority,
and their target user audience can periodically fetch the list of
available community bridges to stay up-to-date. (Default: not set)

V3AuthVotingIntervalNminutes|hours

V3 authoritative directories only. Configures the server’s preferred voting
interval. Note that voting will actually happen at an interval chosen
by consensus from all the authorities' preferred intervals. This time
SHOULD divide evenly into a day. (Default: 1 hour)

V3AuthVoteDelayNminutes|hours

V3 authoritative directories only. Configures the server’s preferred delay
between publishing its vote and assuming it has all the votes from all the
other authorities. Note that the actual time used is not the server’s
preferred time, but the consensus of all preferences. (Default: 5 minutes)

V3AuthDistDelayNminutes|hours

V3 authoritative directories only. Configures the server’s preferred delay
between publishing its consensus and signature and assuming it has all the
signatures from all the other authorities. Note that the actual time used
is not the server’s preferred time, but the consensus of all preferences.
(Default: 5 minutes)

V3AuthNIntervalsValidNUM

V3 authoritative directories only. Configures the number of VotingIntervals
for which each consensus should be valid for. Choosing high numbers
increases network partitioning risks; choosing low numbers increases
directory traffic. Note that the actual number of intervals used is not the
server’s preferred number, but the consensus of all preferences. Must be at
least 2. (Default: 3)

If set, the directory authority will sign consensuses not only with its
own signing key, but also with a "legacy" key and certificate with a
different identity. This feature is used to migrate directory authority
keys in the event of a compromise. (Default: 0)

RephistTrackTimeNseconds|minutes|hours|days|weeks

Tells an authority, or other node tracking node reliability and history,
that fine-grained information about nodes can be discarded when it hasn’t
changed for a given amount of time. (Default: 24 hours)

AuthDirHasIPv6Connectivity0|1

Authoritative directories only. When set to 0, OR ports with an
IPv6 address are being accepted without reachability testing.
When set to 1, IPv6 OR ports are being tested just like IPv4 OR
ports. (Default: 0)

MinMeasuredBWsForAuthToIgnoreAdvertisedN

A total value, in abstract bandwidth units, describing how much
measured total bandwidth an authority should have observed on the network
before it will treat advertised bandwidths as wholly
unreliable. (Default: 500)

HIDDEN SERVICE OPTIONS

The following options are used to configure a hidden service.

HiddenServiceDirDIRECTORY

Store data files for a hidden service in DIRECTORY. Every hidden service
must have a separate directory. You may use this option multiple times to
specify multiple services. If DIRECTORY does not exist, Tor will create it.
(Note: in current versions of Tor, if DIRECTORY is a relative path,
it will be relative to the current
working directory of Tor instance, not to its DataDirectory. Do not
rely on this behavior; it is not guaranteed to remain the same in future
versions.)

HiddenServicePortVIRTPORT &lsqb;TARGET]

Configure a virtual port VIRTPORT for a hidden service. You may use this
option multiple times; each time applies to the service using the most
recent HiddenServiceDir. By default, this option maps the virtual port to
the same port on 127.0.0.1 over TCP. You may override the target port,
address, or both by specifying a target of addr, port, addr:port, or
unix:path. (You can specify an IPv6 target as &lsqb;addr]:port. Unix
paths may be quoted, and may use standard C escapes.)
You may also have multiple lines with the same VIRTPORT: when a user
connects to that VIRTPORT, one of the TARGETs from those lines will be
chosen at random.

PublishHidServDescriptors0|1

If set to 0, Tor will run any hidden services you configure, but it won’t
advertise them to the rendezvous directory. This option is only useful if
you’re using a Tor controller that handles hidserv publishing for you.
(Default: 1)

HiddenServiceVersionversion,version,…

A list of rendezvous service descriptor versions to publish for the hidden
service. Currently, versions 2 and 3 are supported. (Default: 2)

HiddenServiceAuthorizeClientauth-typeclient-name,client-name,…

If configured, the hidden service is accessible for authorized clients
only. The auth-type can either be 'basic' for a general-purpose
authorization protocol or 'stealth' for a less scalable protocol that also
hides service activity from unauthorized clients. Only clients that are
listed here are authorized to access the hidden service. Valid client names
are 1 to 16 characters long and only use characters in A-Za-z0-9+-_ (no
spaces). If this option is set, the hidden service is not accessible for
clients without authorization any more. Generated authorization data can be
found in the hostname file. Clients need to put this authorization data in
their configuration file using HidServAuth.

HiddenServiceAllowUnknownPorts0|1

If set to 1, then connections to unrecognized ports do not cause the
current hidden service to close rendezvous circuits. (Setting this to 0 is
not an authorization mechanism; it is instead meant to be a mild
inconvenience to port-scanners.) (Default: 0)

HiddenServiceMaxStreamsN

The maximum number of simultaneous streams (connections) per rendezvous
circuit. The maximum value allowed is 65535. (Setting this to 0 will allow
an unlimited number of simultanous streams.) (Default: 0)

HiddenServiceMaxStreamsCloseCircuit0|1

If set to 1, then exceeding HiddenServiceMaxStreams will cause the
offending rendezvous circuit to be torn down, as opposed to stream creation
requests that exceed the limit being silently ignored. (Default: 0)

RendPostPeriodNseconds|minutes|hours|days|weeks

Every time the specified period elapses, Tor uploads any rendezvous
service descriptors to the directory servers. This information is also
uploaded whenever it changes. Minimum value allowed is 10 minutes and
maximum is 3.5 days. (Default: 1 hour)

HiddenServiceDirGroupReadable0|1

If this option is set to 1, allow the filesystem group to read the
hidden service directory and hostname file. If the option is set to 0,
only owner is able to read the hidden service directory. (Default: 0)
Has no effect on Windows.

HiddenServiceNumIntroductionPointsNUM

Number of introduction points the hidden service will have. You can’t
have more than 10 for v2 service and 20 for v3. (Default: 3)

HiddenServiceSingleHopMode0|1

Experimental - Non Anonymous Hidden Services on a tor instance in
HiddenServiceSingleHopMode make one-hop (direct) circuits between the onion
service server, and the introduction and rendezvous points. (Onion service
descriptors are still posted using 3-hop paths, to avoid onion service
directories blocking the service.)
This option makes every hidden service instance hosted by a tor instance a
Single Onion Service. One-hop circuits make Single Onion servers easily
locatable, but clients remain location-anonymous. However, the fact that a
client is accessing a Single Onion rather than a Hidden Service may be
statistically distinguishable.

WARNING: Once a hidden service directory has been used by a tor
instance in HiddenServiceSingleHopMode, it can NEVER be used again for
a hidden service. It is best practice to create a new hidden service
directory, key, and address for each new Single Onion Service and Hidden
Service. It is not possible to run Single Onion Services and Hidden
Services from the same tor instance: they should be run on different
servers with different IP addresses.

HiddenServiceSingleHopMode requires HiddenServiceNonAnonymousMode to be set
to 1. Since a Single Onion service is non-anonymous, you can not configure
a SOCKSPort on a tor instance that is running in
HiddenServiceSingleHopMode. Can not be changed while tor is running.
(Default: 0)

HiddenServiceNonAnonymousMode0|1

Makes hidden services non-anonymous on this tor instance. Allows the
non-anonymous HiddenServiceSingleHopMode. Enables direct connections in the
server-side hidden service protocol. If you are using this option,
you need to disable all client-side services on your Tor instance,
including setting SOCKSPort to "0". Can not be changed while tor is
running. (Default: 0)

TESTING NETWORK OPTIONS

The following options are used for running a testing Tor network.

TestingTorNetwork0|1

If set to 1, Tor adjusts default values of the configuration options below,
so that it is easier to set up a testing Tor network. May only be set if
non-default set of DirAuthorities is set. Cannot be unset while Tor is
running.
(Default: 0)

Schedule for when clients should download each bridge descriptor when they
know that one or more of their configured bridges are running. Changing
this requires that TestingTorNetwork is set. (Default: 10800, 25200,
54000, 111600, 262800)

TestingBridgeBootstrapDownloadScheduleN,N,…

Schedule for when clients should download each bridge descriptor when they
have just started, or when they can not contact any of their bridges.
Changing this requires that TestingTorNetwork is set. (Default: 0, 30,
90, 600, 3600, 10800, 25200, 54000, 111600, 262800)

TestingClientMaxIntervalWithoutRequestNseconds|minutes

When directory clients have only a few descriptors to request, they batch
them until they have more, or until this amount of time has passed.
Changing this requires that TestingTorNetwork is set. (Default: 10
minutes)

TestingDirConnectionMaxStallNseconds|minutes

Let a directory connection stall this long before expiring it.
Changing this requires that TestingTorNetwork is set. (Default:
5 minutes)

TestingConsensusMaxDownloadTriesNUM

Try this many times to download a consensus before giving up. Changing
this requires that TestingTorNetwork is set. (Default: 8)

TestingDescriptorMaxDownloadTriesNUM

Try this often to download a server descriptor before giving up.
Changing this requires that TestingTorNetwork is set. (Default: 8)

TestingMicrodescMaxDownloadTriesNUM

Try this often to download a microdesc descriptor before giving up.
Changing this requires that TestingTorNetwork is set. (Default: 8)

TestingCertMaxDownloadTriesNUM

Try this often to download a v3 authority certificate before giving up.
Changing this requires that TestingTorNetwork is set. (Default: 8)

TestingDirAuthVoteExitnode,node,…

A list of identity fingerprints, country codes, and
address patterns of nodes to vote Exit for regardless of their
uptime, bandwidth, or exit policy. See the ExcludeNodes
option for more information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork
has to be set. See the ExcludeNodes option for more
information on how to specify nodes.

TestingDirAuthVoteExitIsStrict0|1

If True (1), a node will never receive the Exit flag unless it is specified
in the TestingDirAuthVoteExit list, regardless of its uptime, bandwidth,
or exit policy.

In order for this option to have any effect, TestingTorNetwork
has to be set.

TestingDirAuthVoteGuardnode,node,…

A list of identity fingerprints and country codes and
address patterns of nodes to vote Guard for regardless of their
uptime and bandwidth. See the ExcludeNodes option for more
information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork
has to be set.

TestingDirAuthVoteGuardIsStrict0|1

If True (1), a node will never receive the Guard flag unless it is specified
in the TestingDirAuthVoteGuard list, regardless of its uptime and bandwidth.

In order for this option to have any effect, TestingTorNetwork
has to be set.

TestingDirAuthVoteHSDirnode,node,…

A list of identity fingerprints and country codes and
address patterns of nodes to vote HSDir for regardless of their
uptime and DirPort. See the ExcludeNodes option for more
information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork
must be set.

TestingDirAuthVoteHSDirIsStrict0|1

If True (1), a node will never receive the HSDir flag unless it is specified
in the TestingDirAuthVoteHSDir list, regardless of its uptime and DirPort.

In order for this option to have any effect, TestingTorNetwork
has to be set.

TestingEnableConnBwEvent0|1

If this option is set, then Tor controllers may register for CONN_BW
events. Changing this requires that TestingTorNetwork is set.
(Default: 0)

TestingEnableCellStatsEvent0|1

If this option is set, then Tor controllers may register for CELL_STATS
events. Changing this requires that TestingTorNetwork is set.
(Default: 0)

TestingEnableTbEmptyEvent0|1

If this option is set, then Tor controllers may register for TB_EMPTY
events. Changing this requires that TestingTorNetwork is set.
(Default: 0)

These underscore-prefixed options are variants of the regular Port
options. They behave the same, except they are not saved to the
torrc file by the controller’s SAVECONF command.

SIGNALS

Tor catches the following signals:

SIGTERM

Tor will catch this, clean up and sync to disk if necessary, and exit.

SIGINT

Tor clients behave as with SIGTERM; but Tor servers will do a controlled
slow shutdown, closing listeners and waiting 30 seconds before exiting.
(The delay can be configured with the ShutdownWaitLength config option.)

SIGHUP

The signal instructs Tor to reload its configuration (including closing and
reopening logs), and kill and restart its helper processes if applicable.

SIGUSR1

Log statistics about current connections, past connections, and throughput.

SIGUSR2

Switch all logs to loglevel debug. You can go back to the old loglevels by
sending a SIGHUP.

SIGCHLD

Tor receives this signal when one of its helper processes has exited, so it
can clean up.

SIGPIPE

Tor catches this signal and ignores it.

SIGXFSZ

If this signal exists on your platform, Tor catches and ignores it.

FILES

@CONFDIR@/torrc

The configuration file, which contains "option value" pairs.

$HOME/.torrc

Fallback location for torrc, if @CONFDIR@/torrc is not found.

@LOCALSTATEDIR@/lib/tor/

The tor process stores keys and other data here.

DataDirectory/cached-status/

The most recently downloaded network status document for each authority.
Each file holds one such document; the filenames are the hexadecimal
identity key fingerprints of the directory authorities. Obsolete;
no longer in use.

DataDirectory/cached-certs

This file holds downloaded directory key certificates that are used to
verify authenticity of documents generated by Tor directory authorities.

DataDirectory/cached-consensus and/or cached-microdesc-consensus

The most recent consensus network status document we’ve downloaded.

DataDirectory/cached-descriptors and cached-descriptors.new

These files hold downloaded router statuses. Some routers may appear more
than once; if so, the most recently published descriptor is used. Lines
beginning with @-signs are annotations that contain more information about
a given router. The ".new" file is an append-only journal; when it gets
too large, all entries are merged into a new cached-descriptors file.

DataDirectory/cached-extrainfo and cached-extrainfo.new

As "cached-descriptors", but holds optionally-downloaded "extra-info"
documents. Relays use these documents to send inessential information
about statistics, bandwidth history, and network health to the
authorities. They aren’t fetched by default; see the DownloadExtraInfo
option for more info.

DataDirectory/cached-microdescs and cached-microdescs.new

These files hold downloaded microdescriptors. Lines beginning with
@-signs are annotations that contain more information about a given
router. The ".new" file is an append-only journal; when it gets too
large, all entries are merged into a new cached-microdescs file.

A set of persistent key-value mappings. These are documented in
the file. These include:

The current entry guards and their status.

The current bandwidth accounting values.

When the file was last written

What version of Tor generated the state file

A short history of bandwidth usage, as produced in the server
descriptors.

DataDirectory/sr-state

Authority only. State file used to record information about the current
status of the shared-random-value voting state.

DataDirectory/diff-cache

Directory cache only. Holds older consensuses, and diffs from older
consensuses to the most recent consensus of each type, compressed
in various ways. Each file contains a set of key-value arguments
decribing its contents, followed by a single NUL byte, followed by the
main file contents.

DataDirectory/bw_accounting

Used to track bandwidth accounting values (when the current period starts
and ends; how much has been read and written so far this period). This file
is obsolete, and the data is now stored in the 'state' file instead.

DataDirectory/control_auth_cookie

Used for cookie authentication with the controller. Location can be
overridden by the CookieAuthFile config option. Regenerated on startup. See
control-spec.txt in torspec for details.
Only used when cookie authentication is enabled.

DataDirectory/lock

This file is used to prevent two Tor instances from using same data
directory. If access to this file is locked, data directory is already
in use by Tor.

DataDirectory/key-pinning-journal

Used by authorities. A line-based file that records mappings between
RSA1024 identity keys and Ed25519 identity keys. Authorities enforce
these mappings, so that once a relay has picked an Ed25519 key, stealing
or factoring the RSA1024 key will no longer let an attacker impersonate
the relay.

DataDirectory/keys/*

Only used by servers. Holds identity keys and onion keys.

DataDirectory/keys/authority_identity_key

A v3 directory authority’s master identity key, used to authenticate its
signing key. Tor doesn’t use this while it’s running. The tor-gencert
program uses this. If you’re running an authority, you should keep this
key offline, and not actually put it here.

DataDirectory/keys/authority_certificate

A v3 directory authority’s certificate, which authenticates the authority’s
current vote- and consensus-signing key using its master identity key.
Only directory authorities use this file.

DataDirectory/keys/authority_signing_key

A v3 directory authority’s signing key, used to sign votes and consensuses.
Only directory authorities use this file. Corresponds to the
authority_certificate cert.

DataDirectory/keys/legacy_certificate

As authority_certificate: used only when V3AuthUseLegacyKey is set.
See documentation for V3AuthUseLegacyKey.

DataDirectory/keys/legacy_signing_key

As authority_signing_key: used only when V3AuthUseLegacyKey is set.
See documentation for V3AuthUseLegacyKey.

DataDirectory/keys/secret_id_key

A relay’s RSA1024 permanent identity key, including private and public
components. Used to sign router descriptors, and to sign other keys.

DataDirectory/keys/ed25519_master_id_public_key

The public part of a relay’s Ed25519 permanent identity key.

DataDirectory/keys/ed25519_master_id_secret_key

The private part of a relay’s Ed25519 permanent identity key. This key
is used to sign the medium-term ed25519 signing key. This file can be
kept offline, or kept encrypted. If so, Tor will not be able to generate
new signing keys itself; you’ll need to use tor --keygen yourself to do
so.

DataDirectory/keys/ed25519_signing_secret_key

The private and public components of a relay’s medium-term Ed25519 signing
key. This key is authenticated by the Ed25519 master key, in turn
authenticates other keys (and router descriptors).

DataDirectory/keys/ed25519_signing_cert

The certificate which authenticates "ed25519_signing_secret_key" as
having been signed by the Ed25519 master key.

DataDirectory/keys/secret_onion_key and secret_onion_key.old

A relay’s RSA1024 short-term onion key. Used to decrypt old-style ("TAP")
circuit extension requests. The ".old" file holds the previously
generated key, which the relay uses to handle any requests that were
made by clients that didn’t have the new one.

DataDirectory/keys/secret_onion_key_ntor and secret_onion_key_ntor.old

A relay’s Curve25519 short-term onion key. Used to handle modern ("ntor")
circuit extension requests. The ".old" file holds the previously
generated key, which the relay uses to handle any requests that were
made by clients that didn’t have the new one.

DataDirectory/fingerprint

Only used by servers. Holds the fingerprint of the server’s identity key.

DataDirectory/hashed-fingerprint

Only used by bridges. Holds the hashed fingerprint of the bridge’s
identity key. (That is, the hash of the hash of the identity key.)

DataDirectory/approved-routers

Only used by authoritative directory servers. This file lists
the status of routers by their identity fingerprint.
Each line lists a status and a fingerprint separated by
whitespace. See your fingerprint file in the DataDirectory for an
example line. If the status is !reject then descriptors from the
given identity (fingerprint) are rejected by this server. If it is
!invalid then descriptors are accepted but marked in the directory as
not valid, that is, not recommended.

DataDirectory/v3-status-votes

Only for v3 authoritative directory servers. This file contains
status votes from all the authoritative directory servers.

DataDirectory/unverified-consensus

This file contains a network consensus document that has been downloaded,
but which we didn’t have the right certificates to check yet.

DataDirectory/unverified-microdesc-consensus

This file contains a microdescriptor-flavored network consensus document
that has been downloaded, but which we didn’t have the right certificates
to check yet.

DataDirectory/unparseable-desc

Onion server descriptors that Tor was unable to parse are dumped to this
file. Only used for debugging.

DataDirectory/router-stability

Only used by authoritative directory servers. Tracks measurements for
router mean-time-between-failures so that authorities have a good idea of
how to set their Stable flags.

DataDirectory/stats/dirreq-stats

Only used by directory caches and authorities. This file is used to
collect directory request statistics.

DataDirectory/stats/entry-stats

Only used by servers. This file is used to collect incoming connection
statistics by Tor entry nodes.

DataDirectory/stats/bridge-stats

Only used by servers. This file is used to collect incoming connection
statistics by Tor bridges.

DataDirectory/stats/exit-stats

Only used by servers. This file is used to collect outgoing connection
statistics by Tor exit routers.

DataDirectory/stats/buffer-stats

Only used by servers. This file is used to collect buffer usage
history.

DataDirectory/stats/conn-stats

Only used by servers. This file is used to collect approximate connection
history (number of active connections over time).

DataDirectory/stats/hidserv-stats

Only used by servers. This file is used to collect approximate counts
of what fraction of the traffic is hidden service rendezvous traffic, and
approximately how many hidden services the relay has seen.

DataDirectory/networkstatus-bridges

Only used by authoritative bridge directories. Contains information
about bridges that have self-reported themselves to the bridge
authority.

DataDirectory/approved-routers

Authorities only. This file is used to configure which relays are
known to be valid, invalid, and so forth.

HiddenServiceDirectory/hostname

The <base32-encoded-fingerprint>.onion domain name for this hidden service.
If the hidden service is restricted to authorized clients only, this file
also contains authorization data for all clients.
Note that clients will ignore any extra subdomains prepended to a hidden
service hostname. So if you have "xyz.onion" as your hostname, you
can tell clients to connect to "www.xyz.onion" or "irc.xyz.onion"
for virtual-hosting purposes.

HiddenServiceDirectory/private_key

The private key for this hidden service.

HiddenServiceDirectory/client_keys

Authorization data for a hidden service that is only accessible by
authorized clients.

HiddenServiceDirectory/onion_service_non_anonymous

This file is present if a hidden service key was created in
HiddenServiceNonAnonymousMode.